Methods and apparatus for selecting and transmitting pilots

ABSTRACT

Sets of communications resources, e.g., sets of peer discovery resources, in a peer to peer communications system may be use concurrently by multiple transmitting devices. The communications system supports a plurality of different pilot sequences. Multiple transmitting devices may transmit their signals on the same set of communications resources, but with different pilot sequences. This approach allows receiving devices to distinguish between multiple signal sources, e.g., wireless terminals, using a shared communications resource. A wireless communications device monitors a plurality of different sets of communications resources and selects, e.g., based on received energy levels, a set of communications resources from said plurality of different sets of communications resources to use for communication. The communications device further selects one of a plurality of different pilot sequences to use for said communication and transmits pilot signals using the selected pilot sequence and at least a portion of the selected set of communications resources.

FIELD

Various embodiments relate to wireless communications, and moreparticularly, to methods and apparatus for communicating information ina system where air link resources may be, and sometimes are, reused.

BACKGROUND

In ad-hoc wireless networks, e.g., peer to peer wireless communicationssystems, there may be a large number of wireless communications devicesin a local vicinity at any given time. It would be beneficial if a peerto peer wireless device could communicate small amounts of information,e.g., discovery information, relatively frequently to other deviceswhich may happen to be in its vicinity. It should be expected that theother devices, e.g., intended recipients, may not be maintaining ongoingchannel estimates with one another.

Due to the number of anticipated devices that may be concurrentlyoperating in a local vicinity and the limited amount of air linkresources available to support signaling, e.g., peer discoverysignaling, it may be desirable for multiple transmitting devices toconcurrently use the same set of communications resources. Based on theabove discussion, it should be appreciated there is a need for methodsand apparatus facilitating concurrent use of a set of communicationsresources by multiple transmitting devices.

SUMMARY

Methods and apparatus of communicating information in a wirelesscommunications system using shared resources are described. Variousdescribed methods and apparatus are well suited for use in ad-hocnetworks, e.g., peer to peer wireless communications systems, in whichresource utilization decisions for at least some types of air linkresources are made in a decentralized manner, e.g., by individualtransmitting devices. In some ad-hoc peer to peer networks wirelessterminals directly communicate with one another without the involvementof a central network controller. Various features are particularlyadvantageous to embodiments in which a large number of users may becompeting for a limited number of sets of communications resources, andthe sets of resources may be, and sometimes are, anticipated to be usedconcurrently by multiple transmitting devices in the network.

In one exemplary embodiment, the sets of communications resources aresets of peer discovery resources in a wireless peer to peercommunications system. In some but not all embodiments, a set of peerdiscovery communications resources is a set of OFDM tone-symbolscorresponding to a single OFDM tone for a predetermined number ofconsecutive OFDM symbol transmission time periods. In some embodimentssets of peer discovery resources occur during peer discovery intervalsas part of a recurring peer to peer timing structure.

In some embodiments, a wireless device may transmit, e.g., broadcast, arelatively small amount of peer discovery information relativelyfrequently. The peer discovery information is intended to be availableto be received and recovered by other peer to peer wireless deviceswhich may be in its local vicinity. An intended recipient device may ormay not have an ongoing channel estimate with respect to thetransmitting device. Embedded pilot signals, communicated in a portionof a peer discovery resource set used to communicate discoveryinformation, are used to facilitate peer discovery information recovery.

The exemplary peer to peer communications system supports a plurality ofdifferent alternative pilot sequences. Multiple transmitting devices maytransmit their peer discovery signals on the same set of peer discoveryresources, but may use different pilot sequences. This allows areceiving device to distinguish between signals from different devices.In various embodiments, the sets of different pilot sequences areorthogonal. In some embodiments, the sets of different pilot sequencesare Walsh sequences. In some embodiments, the sets of different pilotsequences are Fourier sequences. The use of different pilot sequences,corresponding to different transmitting devices, over a common air linkresource, facilitates the recovery and separation of receivedinformation by a receiving device from multiple transmitting sources.

A wireless communications device, which intends to transmit peerdiscovery signals, makes two levels of selection, e.g., a selection of aset of peer discovery communications resources and a selection of apilot sequence to use. The wireless communications device transmitssignals including pilot signals, in accordance with its selected pilotsequence, and data signals using its selected set of peer discoverycommunications resources.

An exemplary method of operating a communications device to communicateinformation, in accordance with some embodiments, comprises: monitoringa plurality of different sets of communications resources; determiningthe amount of energy received on at least a first portion of saiddifferent sets of communications resources; and selecting a set ofcommunications resources from said plurality of different sets ofcommunications resources to use for communication. The exemplary methodfurther comprises: selecting one of a plurality of different pilotsequences to use for said communication; and transmitting pilot signalsusing the selected one of the plurality of different pilot sequences andat least a second portion of the selected set of communicationsresources.

An exemplary communications device, in accordance with some embodiments,comprises: at least one processor configured to: monitor a plurality ofdifferent sets of communications resources; determine the amount ofenergy received on at least a first portion of said different sets ofcommunications resources; select a set of communications resources fromsaid plurality of different sets of communications resources to use forcommunication; select one of a plurality of different pilot sequences touse for said communication; and transmit pilot signals using theselected one of the plurality of different pilot sequences and at leasta second portion of the selected set of communications resources. Theexemplary communications device further includes memory coupled to saidat least one processor. The exemplary communications device is, e.g., awireless terminal, e.g., a mobile device such as a handheld phonedevice, handheld personal data assistant (PDA), etc.

While various embodiments have been discussed in the summary above, itshould be appreciated that not necessarily all embodiments include thesame features and some of the features described above are not necessarybut can be desirable in some embodiments. Numerous additional features,embodiments and benefits of various embodiments are discussed in thedetailed description which follows.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a drawing of an exemplary peer to peer communications systemin accordance with an exemplary embodiment.

FIG. 2 is a flowchart of an exemplary method of operating acommunications device to communicate information in accordance with anexemplary embodiment.

FIG. 3 is a drawing of an exemplary communications device, in accordancewith an exemplary embodiment.

FIG. 4 is an assembly of modules which can, and in some embodiments is,used in the communications device illustrated in FIG. 3.

FIG. 5 is a drawing of an exemplary frequency vs time plot illustratingexemplary air link resources in an exemplary peer to peer recurringtiming structure.

FIG. 6 is a drawing of an exemplary frequency vs time plot illustratingexemplary peer discovery air link resources in an exemplary peer to peerrecurring timing structure.

FIG. 7 is a drawing of an exemplary frequency vs time plot illustratingexemplary peer discovery resource sets within the peer discoveryresource blocks illustrated in FIG. 6.

FIG. 8 is a drawing illustrating an exemplary peer discovery resourceset, which may be any of the peer discovery resource sets of FIG. 7.

FIG. 9 is a drawing illustrating an exemplary peer discovery resourceset used to carry pilot and data symbols.

FIG. 10 is a drawing illustrating a table of exemplary alternative pilotsequences and a plot illustrating mapping of a set of two pilot symbolsto a complex plane.

FIG. 11 is a drawing illustrating a table of exemplary alternative pilotsequences and a plot illustrating mapping of a set of four pilot symbolsto a complex plane.

FIG. 12 is a drawing illustrating two examples in which a pilot sequenceof FIG. 11 is selected for transmission in an exemplary peer discoveryresource set described with respect to FIG. 9.

FIG. 13 is a drawing illustrating an example in which device 1 of thesystem of FIG. 1 decides that it would like to transmit, e.g.,broadcast, peer discovery information, monitors a plurality of differentsets of peer discovery resources, and selects a peer discovery resourceset and a peer discovery pilot sequence as a function of the monitoredinformation.

FIG. 14 is a drawing illustrating exemplary wireless terminal 1measurements and operations corresponding to the FIG. 13 exemplaryscenario.

FIG. 15 is a flowchart an exemplary method of operating a communicationsdevice to communicate information in accordance with an exemplaryembodiment.

FIG. 16 is a drawing of an exemplary communications device, inaccordance with an exemplary embodiment.

FIG. 17 is an assembly of modules which can, and in some embodiments is,used in the communications device illustrated in FIG. 16.

FIG. 18 illustrates four examples of exemplary coding information thatmay be communicated via pilot signals via non-coherent modulation.

FIG. 19 is a flowchart 1900 of an exemplary method of operating acommunications device to communicate information, e.g., to communicatepeer discovery information, in accordance with an exemplary embodiment.

FIG. 20 is a drawing illustrating an exemplary peer discovery resourceset used to carry pilot and data symbols.

FIG. 21 is a flowchart of an exemplary method of operating acommunications device to recover information communicated by first andsecond devices using a set of communications resources.

FIG. 22 is a drawing of an exemplary communications device, inaccordance with an exemplary embodiment.

FIG. 23 is an assembly of modules which can, and in some embodiments is,used in the communications device illustrated in FIG. 22.

FIG. 24 is a drawing illustrating an example in which a wirelesscommunications device, e.g., a wireless terminal, recovers informationcommunicated by two other wireless communications devices using a set ofcommunications resources in accordance with an exemplary embodiment.

DETAILED DESCRIPTION

FIG. 1 is a drawing of an exemplary peer to peer communications system100 in accordance with an exemplary embodiment. Exemplary peer to peercommunications system 100 includes a plurality of wirelesscommunications devices (device 1 102, device 2 104, device 3 106, device4 108, device 5 110, device 6 112, device 7 114, . . . , device N 116.Some of the wireless communications devices, e.g., device 1 102, device2 104, device 3 106, device 5 110, device 6 112, device 7 114, anddevice N 116, are mobile wireless communications devices, e.g., handheldwireless terminals supporting peer to peer communications. Some of thewireless communications devices, e.g., device 4 108, include aninterface 118, e.g., a wired or fiber optic interface, coupling thedevice to the Internet and/or other network nodes via a backhaulnetwork. Device 4 108 is, e.g., an access point supporting peer to peercommunications. Peer to peer communications system 100 uses a recurringpeer to peer timing structure including sets of peer discoveryresources. A wireless communications device, e.g., device 1 102, whichdesires to transmit, e.g., broadcast, peer discovery information,monitors different sets of peer discovery resources, selects a set ofpeer discovery resources to use to transmit its peer discoveryinformation, selects a pilot sequence to use for its peer discoverysignals, and generates and transmits peer discovery signals includingpilots symbols and data symbols using the selected peer discoveryresource set.

FIG. 2 is a flowchart 200 of an exemplary method of operating acommunications device to communicate information. The communicationsdevice implements the method of flowchart 200 of FIG. 2 is, e.g., one ofthe devices (102, 104, 106, 108, 1110, 112, 114, . . . , 116) of system100 of FIG. 1. In some embodiments, the communications device is adevice in an ad hoc communications network, e.g., a peer to peercommunications network. In various embodiments, the communicationsdevice is a mobile wireless terminal, e.g., a handheld communicationsdevice. Operation starts in step 202 where the communications device ispowered on and initialized and proceeds to step 204.

In step 204 the communications device monitors a plurality of differentsets of communications resources. In some embodiments, the differentsets of communications resources are sets of peer discovery resourceswhich recur in a predetermined timing structure used to control timingin a communications network in which the communications device, e.g.,wireless communications device, is located. In various embodiments, anindividual communications resource in a set of communications resourcesis a tone-symbol, e.g., an OFDM tone-symbol, and a signal transmitted onan individual communications resource is a modulation symbol. In someembodiments, each set of communications resources is a set of contiguousOFDM tone-symbols corresponding to a single tone for a predeterminednumber of symbol transmission time periods.

Operation proceeds from step 204 to step 206. In step 206 thecommunications device determines the amount of energy received on atleast a first portion of said different sets of communicationsresources. In some embodiments, a first portion of a set ofcommunications resources is the full set of individual communicationsresources in the set of communications resources. In some otherembodiments, a first portion of a set of communications resourcesincludes individual communications resources in the set associated withpilot symbols but does not include individual communications resourcesin the set associated with data symbols. Then in step 208 thecommunications device selects a set of communications resources fromsaid plurality of different sets of communications resources to use forcommunication. In some embodiments, in step 208 the communicationsdevice selects a set of communications resources based on the determinedamount of energy received on said at least a first portion of saiddifferent sets of communications resources, which was determined in step206.

In some embodiments, optional step 210 is included and operationproceeds from step 208 to step 210. In other embodiments optional step210 is not included and operation proceeds from step 208 to step 212.

Returning to step 210, in step 210 the communications device determinesthe amount of energy attributable to signals corresponding to differentones of said plurality of different pilot sequences. Operation proceedsfrom step 210 to step 212.

In step 212 the communications device selects one of a plurality ofdifferent pilot sequences to use for said communication. In someembodiments, the different pilot sequences in said plurality ofdifferent pilot sequences are orthogonal. In some such embodiments, thedifferent pilot sequences are Fourier sequences. In some embodiments,the different pilot sequences in said plurality of different pilotsequences include pilots which differ in phase but not amplitude. Insome embodiments the different pilot sequences are Walsh sequences.Other types of pilot sequences may be, and in some embodiments, areused, e.g., other pilot sequences based on a well-designed non-coherentcode.

In some embodiments, step 212 includes one or more of step 214 and 216.In step 214 the communications devices makes a pseudo random selectionof one of the plurality of different pilot sequences. In step 216 thecommunications device selects one of the plurality of different pilotsequences based on the determined amount energy attributable to thedifferent ones of the plurality of pilot sequences. In some embodimentsstep 216 includes step 218 in which the communications device selectsthe pilot sequence which has the lowest amount of energy attributed toit. In some other cases the communications device selects the pilotsequence from among a predetermined number of pilots sequences havingthe lowest amounts of energy, e.g., the communications devices selectsone of the two lowest power pilot sequences. In some other cases thecommunications device selects the pilot sequence from among any of thepilot sequences having an energy level below a threshold, e.g., thecommunications devices selects one of pilot sequences among any of thecandidate pilot sequences which have energy levels below a predeterminedthreshold. Operation proceeds from step 212 to step 220.

In step 220 the communications device transmits pilot signals using theselected one of the plurality of different pilot sequences and at leasta second portion, e.g., a pilot portion, of the selected set ofcommunications resources. In some embodiments, step 220 include step 222in which the communications device introduces a first uniform phaserotation from one pilot signal to the next to produce a Fouriersequence.

In various embodiments, the exemplary method includes one or more ofsteps 224 and 226. Operation proceeds from step 220 to step 224, inwhich the communications device introduces a second uniform phaserotation, which is a function of the first uniform phase rotation, intodata symbols to be transmitted using a third portion of the selected setof communications resources, said third portion not including saidsecond portion. Operation proceeds from step 224 to step 226. In step226 the communications device changes to a different one of theplurality of pilot sequences during a second time period, which issubsequent to a first time period, according to a predeterminedfunction. In some such embodiments, the selecting one of a plurality ofdifferent pilot sequences of step 212 was for the first time period. Invarious embodiments, the second time period is immediately subsequentthe first time period. In some embodiments, the predetermined functionused in step 226 is a hopping or pseudo random function.

FIG. 3 is a drawing of an exemplary communications device 300, inaccordance with an exemplary embodiment. Exemplary communications device300 is, e.g., one of the wireless communications devices of FIG. 1.Exemplary communications device 300 may, and sometimes does, implement amethod in accordance with flowchart 200 of FIG. 2.

Communications device 300 includes a processor 302 and memory 304coupled together via a bus 309 over which the various elements (302,304) may interchange data and information. Communications device 300further includes an input module 306 and an output module 308 which maybe coupled to processor 302 as shown. However, in some embodiments, theinput module 306 and output module 308 are located internal to theprocessor 302. Input module 306 can receive input signals. Input module306 can, and in some embodiments does, include a wireless receiverand/or a wired or optical input interface for receiving input. Outputmodule 308 may include, and in some embodiments does include, a wirelesstransmitter and/or a wired or optical output interface for transmittingoutput.

Processor 302 is configured to: monitor a plurality of different sets ofcommunications resources; determine the amount of energy received on atleast a first portion of said different sets of communicationsresources; and select a set of communications resources from saidplurality of different sets of communications resources to use forcommunication. In some embodiments, the first portion of said differentsets of communications resources includes each of the individualcommunications resources in said different sets of communicationsresources. In some other embodiments, the first portion of saiddifferent sets of communications resources includes only individualcommunications resources which are pilot communications resources.Processor 302 is further configured to: select one of a plurality ofdifferent pilot sequences to use for said communication; and transmitpilot signals using the selected one of the plurality of different pilotsequences and at least a second portion, e.g., a pilot portion, of theselected set of communications resources.

In some embodiments, processor 302 is configured to base said selectionof a set of communications resources on the determined amount of energyreceived on said at least a first portion of said different sets ofcommunications resources, as part of being configured to select a set ofcommunications resources.

In various embodiments, the communications device 300 is a device in anad hoc communications network. In some embodiments, the communicationsdevice 300 is a mobile wireless terminal, e.g., a handheldcommunications device. In some such embodiments, said ad hoccommunications network is a peer to peer communications network.

In some embodiments, said different pilot sequences in said plurality ofdifferent pilot sequences are orthogonal. In some such embodiments, saiddifferent pilot sequences are Fourier sequences.

Processor 302, in some embodiments, is configured to introduce a firstuniform phase rotation from one pilot signal to the next to produce saidFourier sequence, as part of being configured to transmit pilot signals;and processor 302 is further configured to introduce a second uniformphase rotation which is a function of the first uniform phase rotationinto data symbols to be transmitted using a third portion of theselected set of communications resources, said third portion notincluding said second portion.

In some embodiments, said different pilot sequences are Walsh sequences.In various embodiments, said different pilot sequences in said pluralityof different pilot sequences include pilots which differ in phase butnot amplitude.

Processor 302, in some embodiments, is configured to make a pseudorandom selection of one of the plurality of different pilot sequences,as part of being configured to select one of a plurality of differentpilot sequences. In some such embodiments, processor 302 is configuredto select one of a plurality of different pilot sequences was for afirst time period as part of being configured to select one of aplurality of different pilot sequences; and processor 302 is furtherconfigured to change to a different one of the plurality of differentpilot sequences and use the different one of the plurality of pilotsequences during a second time period which is subsequent to said firsttime period according to a predetermined function. In some embodiments,the second time period is an immediately subsequent time period of thesame type with respect to the first time period. For example, the firsttime period corresponds to indexed peer discovery time period #1 and thesecond time period corresponds to indexed peer discovery time period #2in a peer to peer recurring timing structure. In some embodiments, thepredetermined function is one of a hopping or pseudo random function.

Processor 302, in some embodiments, is further configured to: determinethe amount of energy attributable to signals corresponding to differentones of said plurality of different pilot sequences; and select one ofthe plurality of different pilot sequences based on the determinedamount of energy attributable to the different individual ones of theplurality of pilot sequences. In some such embodiments, processor 302 isconfigured to select the pilot sequence which has the lowest amount ofenergy attributed to it, as part of being configured to select one of aplurality of different pilot sequences. In some other cases, processor302 is configured to select one of a predetermined number of pilotsequences determined to have the lowest attributable energy, as part ofbeing configured to select one of a plurality of different pilotsequences. For example, in one such embodiment, processor 302 isconfigured to select, e.g., pseudo randomly select, one of the twolowest received power pilot sequences, as part of being configured toselect one of a plurality of different pilot sequences.

In some embodiments, said different sets of communications resources aresets of peer discovery resources which recur in a predetermined timingstructure used to control timing in a communications network in whichsaid wireless communications device is located. In various embodiments,an individual communications resource in said communications resourcesis a tone-symbol; and a signal transmitted on an individualcommunications resource is a modulation symbol. In some embodiments,each set of communication resources is a set of contiguous OFDMtone-symbols corresponding to a single tone for a predetermined numberof symbol transmission time periods. For example, in one embodiment, aset of peer discovery communications resources corresponds to one tonefor 16 consecutive OFDM symbol transmission time periods. In anotherembodiment, a set of peer discovery communications resources correspondsto one tone for 64 consecutive OFDM symbol transmission time periods.

FIG. 4 is an assembly of modules 400 which can, and in some embodimentsis, used in the communications device 300 illustrated in FIG. 3. Themodules in the assembly 400 can be implemented in hardware within theprocessor 302 of FIG. 3, e.g., as individual circuits. Alternatively,the modules may be implemented in software and stored in the memory 304of the communications device 300 shown in FIG. 3. While shown in theFIG. 3 embodiment as a single processor, e.g., computer, it should beappreciated that the processor 302 may be implemented as one or moreprocessors, e.g., computers. When implemented in software the modulesinclude code, which when executed by the processor, configure theprocessor, e.g., computer, 302 to implement the function correspondingto the module. In some embodiments, processor 302 is configured toimplement each of the modules of the assembly of modules 400. Inembodiments where the assembly of modules 400 is stored in the memory304, the memory 304 is a computer program product comprising a computerreadable medium comprising code, e.g., individual code for each module,for causing at least one computer, e.g., processor 302, to implement thefunctions to which the modules correspond.

Completely hardware based or completely software based modules may beused. However, it should be appreciated that any combination of softwareand hardware (e.g., circuit implemented) modules may be used toimplement the functions. As should be appreciated, the modulesillustrated in FIG. 4 control and/or configure the communications device300 or elements therein such as the processor 302, to perform thefunctions of the corresponding steps illustrated in the method flowchart200 of FIG. 2.

Assembly of modules 400 includes a module 404 for monitoring a pluralityof different sets of communications resources, a module 406 fordetermining the amount of energy received on at least a first portion ofsaid different sets of communications resources, and a module 408 forselecting a set of communications resources from said plurality ofdifferent sets of communications resources to use for communications.Assembly of modules 400 further includes a module 412 for selecting oneof a plurality of different pilot sequences to use for saidcommunication, and a module 420 for transmitting pilot signals using theselected one of the plurality of different pilot sequences and at leasta second portion of the selected set of communications resources.

In some embodiments, assembly of modules 400 further includes a module410 for determining the amount of energy attributable to signalscorresponding to different ones of said plurality of different pilotsequences. In some embodiments module 412 includes one or more of amodule 414 for making a pseudo random selection of one of the pluralityof different pilot sequences and a module 416 for selecting one of theplurality of different pilot sequences based on the determined amount ofenergy attributable to the different individual ones of the plurality ofpilot sequences. In some embodiments module 416 includes a module 418for selecting the pilot sequence which has the lowest amount of energyattributed to it. In some embodiments, module 416 includes a module 419for selecting the pilot sequence as one of a predetermined number ofpilot sequences with the lowest amounts of determined attributableenergy. For example, in some embodiments, module 419 pseudo-randomlyselects the pilot sequence from among the two pilot sequences determinedto have the lowest amounts of attributable energy.

In some embodiments, module 420 includes a module 422 for introducing afirst uniform phase rotation from one pilot signal to the next toproduce a Fourier sequence. In some such embodiments, assembly ofmodules 400 further includes a module 424 for introducing a seconduniform phase rotation which a function of the first uniform phaserotation into data symbols to be transmitted using a third portion ofthe selected set of communications resources, said third portion of theselected set of communications resources not including said secondportion.

In some embodiments, assembly of modules 400 further includes a module426 for changing to a different one of the plurality of different pilotsequences and using the different one of the plurality of pilotsequences during a second time period, which is subsequent to a firsttime period during which the selected one of the plurality of differentpilot sequences was used, according to a predetermined function.

FIG. 5 is a drawing of an exemplary frequency vs time plot 500illustrating exemplary air link resources in an exemplary peer to peerrecurring timing structure. Frequency vs time plot 500 include avertical axis 502 representing frequency, e.g., OFDM tones, and ahorizontal axis 504 representing time, e.g., OFDM symbol transmissiontime intervals. Plot 500 includes peer discovery air link resource 506,peer to peer connection establishment air link resources 508, peer topeer traffic air link resources 510 and other air link resources 512.

FIG. 6 is a drawing of an exemplary frequency vs time plot 600illustrating exemplary peer discovery air link resources in an exemplarypeer to peer recurring timing structure. Frequency vs time plot 600include a vertical axis 601 representing frequency, e.g., OFDM tones,and a horizontal axis 603 representing time, e.g., OFDM symboltransmission time intervals. In this example, there are M discoveryintervals (discovery interval 1 608, discovery interval 2 610, . . . ,discovery interval M 612) in the recurring timing structure. Peerdiscovery air link resources 602 occurs during discovery interval 1 608;peer discovery air link resources 604 occurs during discovery interval 2610; and peer discovery air link resources 606 occurs during discoveryinterval M 612. Peer discovery air link resource 506 of FIG. 5 is, e.g.,any of the peer discovery air link resource blocks (602, 604, 606) ofFIG. 6.

FIG. 7 is a drawing of an exemplary frequency vs time plot 700illustrating exemplary peer discovery resource sets within the peerdiscovery resource blocks illustrated in FIG. 6. Peer discovery air linkresources block 602 includes, in order from highest to lowest frequency,peer discovery resource set 1 702, peer discovery resource set 2 704,peer discovery resource set 3 706, peer discovery resource set 4 708,peer discovery resource set 5 710, peer discovery resource set 6 712,peer discovery resource set 7 714, peer discovery resources set 8 716,peer discovery resource set 9 718, peer discovery resource set 10 720,peer discovery resource set 11 722, peer discovery resource set 12 724,peer discovery resource set 13 726, and peer discovery resource set 14728. Peer discovery air link resources block 604 includes, in order fromhighest to lowest frequency, peer discovery resource set 10 732, peerdiscovery resource set 12 734, peer discovery resource set 4 736, peerdiscovery resource set 14 738, peer discovery resource set 7 740, peerdiscovery resource set 8 742, peer discovery resource set 5 744, peerdiscovery resources set 11 746, peer discovery resource set 13 748, peerdiscovery resource set 6 750, peer discovery resource set 1 752, peerdiscovery resource set 2 754, peer discovery resource set 9 756, andpeer discovery resource set 3 758. Peer discovery air link resourcesblock 606 includes, in order from highest to lowest frequency, peerdiscovery resource set 14 762, peer discovery resource set 1 764, peerdiscovery resource set 11 766, peer discovery resource set 8 768, peerdiscovery resource set 6 770, peer discovery resource set 7 772, peerdiscovery resource set 2 774, peer discovery resources set 13 776, peerdiscovery resource set 4 778, peer discovery resource set 10 780, peerdiscovery resource set 12 782, peer discovery resource set 3 784, peerdiscovery resource set 5 786, and peer discovery resource set 9 788.

In the example of FIG. 7, a resource set associated with a peerdiscovery identifier hops from one tone to another from one peerdiscovery resource block to another in accordance with a predeterminedhopping scheme. A wireless terminal may acquire and hold a peerdiscovery resource set, corresponding to a peer discovery identifier,for multiple peer discovery resource blocks to use to transmit its peerdiscovery signals. For example, consider that an exemplary wirelessterminal selects peer discovery resource set 1 to use for its peerdiscovery transmissions, in peer discovery resource block 602 thewireless terminal uses peer discovery resource set 1 702 correspondingto the highest frequency, in peer discovery resource block 2 604 thewireless terminal used peer discovery resource set 1 752 correspondingto the fourth lowest frequency, and in peer discovery resource block 606the wireless terminal uses peer discovery resource set 1 764corresponding to the frequency which is 1 step lower than the highestfrequency.

In the example of FIG. 7 a peer discovery resource block is partitionedinto 14 exemplary peer discovery resource sets. In other examples, apeer discovery resource block may include a different number of peerdiscovery resource sets. In some such embodiments, a peer discoveryresource block includes greater than 100 peer discovery resource sets.In some embodiments, the same peer discovery resource sets are notnecessarily included in each successive peer discovery resource block.In some embodiments, there may be multiple peer discovery resource setscorresponding to the same tone in a peer discovery resource block, e.g.,a first peer discovery resource set for a first time interval and asecond peer discovery resource set for a second time interval.

FIG. 8 is a drawing 800 illustrating exemplary peer discovery resourceset i 802. Exemplary peer discovery resource set i 802 may be any of thepeer discovery resource sets illustrated in FIG. 7. Peer discoveryresource set i 802 includes 1 tone 804 for the time duration of K OFDMsymbol transmission time periods 806. Exemplary peer discovery resourceset i 802 may be represented as K OFDM tone-symbols (OFDM tone-symbol 1808, OFDM tone-symbol 2 810, OFDM tone-symbol 3 812, OFDM tone-symbol 4814, OFDM tone-symbol 5 816, OFDM tone-symbol 6 818, . . . , OFDMtone-symbol K 820). Exemplary peer discovery resource set i 802 may beany of the peer discovery resource sets illustrated in FIG. 7. In someembodiments, K is an integer greater than or equal to eight. In oneexemplary embodiment K=16, and there are 16 OFDM tone-symbols in a peerdiscovery resource set. In another exemplary embodiment K=64, and thereare 64 OFDM tone-symbols in a peer discovery resource set. In someembodiments, K_(P) of the K tone-symbols are pilot tone-symbols, whereK/K_(P)≧4. In one embodiment K=64 and K_(P)=8. In some embodiments, thefull set of K tone-symbols correspond to the same tone.

FIG. 9 is a drawing 900 illustrating an exemplary peer discoveryresource set 902 used to carry pilot and data symbols. Peer discoveryresource set 902 is, e.g., peer discovery resource set 804 of FIG. 8,where K=16 and Kp=4. Exemplary peer discovery resource set 902 includes16 indexed OFDM tone-symbols (tone-symbol 1 904, tone symbol 2 906,tone-symbol 3 908, tone-symbol 4 910, tone-symbol 5 912, tone-symbol 6914, tone-symbol 7 916, tone-symbol 8 918, tone-symbol 9 920,tone-symbol 10 922, tone-symbol 11 924, tone-symbol 12 926, tone-symbol13 928, tone-symbol 14 930, tone-symbol 15 932 and tone-symbol 16 934).

Diagonal line shading, as indicated by box 938 of legend 936, indicatesthat an OFDM tone-symbol of the peer discovery resource set is used tocarry a pilot symbol. Horizontal line shading, as indicated by box 940of legend 936, indicates that an OFDM tone-symbol of the peer discoveryresource set is used to carry a data symbol. In this example a firstsubset of tone-symbols (906, 914, 922 and 930) are designated to be usedto carry pilot symbols, while a second non-overlapping subset oftone-symbols (904, 908, 910, 912, 916, 918, 920, 924, 926, 928, 932,934) are used to carry the data symbols. In this example, the spacingbetween pilot designated tone-symbols is uniform with multiple datasymbol designated tone-symbols being interspaced between the pilotdesignated tone-symbols. In some embodiments, the spacing between pilotdesignated tone-symbols is substantially uniform. In one embodiment, thetone-symbols designated to carry pilot symbols temporally precede thetone-symbols designated to carry data symbols. In some embodiments, thefirst and last tone-symbols of the peer discovery resource set aredesignated to carry pilot symbols.

In the example of FIG. 9, tone-symbols (906, 914, 922 and 930) carrypilot symbols (P1 944, P2 952, P3 960 and P4 968), respectively. In theexample of FIG. 9, tone-symbols (904, 908, 910, 912, 916, 918, 920, 924,926, 928, 932, 934) carry data symbols (D1 942, D2 946, D3 948, D4 950,D5 954, D6 956, D7 958, D8 962, D9 964, D10 966, D11 970, D12 972),respectively.

FIG. 10 is a drawing 1000 illustrating a table of exemplary alternativepilot sequences 1002 and a plot illustrating mapping of a set of twopilot symbols to a complex plane. Plot 1004 includes horizontal axis1006 representing the real axis and vertical axis 1008 representing theImaginary axis. Pilot symbol designated as “+” 1010 maps along the realaxis with a phase angle of 0 degrees, while a pilot symbol designated as“−” 1012 maps along the real axis with a phase angle of 180 degrees. Thetransmit power level of the “+” pilot symbol is the same as the transmitpower level of the “−” pilot symbol.

Table 1002 includes a first column 1014 representing pilot sequencenumber, a second column 1016 identifying pilot symbol 1 for each of thealternative pilot sequences, a third column 1018 identifying pilotsymbol 2 for each of the alternative pilot sequences, a fourth column1020 identifying pilot symbol 3 for each of the alternative pilotsequences, and a fifth column 1022 identifying pilot symbol 4 for eachof the alternative pilot sequences. First row 1024 indicates that pilotsequence 1 follows the pattern +, +, +, +. Second row 1026 indicatesthat pilot sequence 2 follows the pattern +, +, −, −. Third row 1028indicates that pilot sequence 3 follows the pattern +, −, +, −. Fourthrow 1030 indicates that pilot sequence 4 follows the pattern +, −, −, +.

FIG. 11 is a drawing 1100 illustrating a table of exemplary alternativepilot sequences 1102 and a plot illustrating mapping of a set of fourpilot symbols to a complex plane. The FIG. 11 embodiment is analternative to the FIG. 10 embodiment. Plot 1104 includes horizontalaxis 1106 representing the real axis and vertical axis 1108 representingthe Imaginary axis. Pilot symbol 1110 designated as “P_(A)” maps alongthe positive real axis corresponding to a phase angle of 0 degrees.Pilot symbol 1112 designated as “P_(B)” maps along the positiveImaginary axis corresponding to a phase angle of 90 degrees. Pilotsymbol 1114 designated as “P_(c)” maps along the negative real axiscorresponding to a phase angle of 180 degrees. Pilot symbol 1116designated as “P_(D)” maps along the negative Imaginary axiscorresponding to a phase angle of 270 degrees. The transmit power levelfor each of the pilot symbols P_(A), P_(B), P_(C) and P_(D) is the same.

Table 1102 includes: a first column 1118 representing pilot sequencenumber, a second column 1120 identifying the amount of phase rotation inradians between successive pilot symbols in a pilot sequence, a thirdcolumn 1122 identifying pilot symbol 1 for each of the alternative pilotsequences, a fourth column 1124 identifying pilot symbol 2 for each ofthe alternative pilot sequences, a fifth column 1126 identifying pilotsymbol 3 for each of the alternative pilot sequences, a sixth column1128 identifying pilot symbol 4 for each of the alternative pilotsequences. First row 1130 indicates that pilot sequence 1 corresponds toa phase rotation of π/2 and follows the pattern P_(A), P_(B), P_(C),P_(D). Second row 1132 indicates that pilot sequence 2 corresponds to aphase rotation of π and follows the pattern P_(A), P_(C), P_(A), P_(C).Third row 1134 indicates that pilot sequence 3 corresponds to a phaserotation of 3π/2 and follows the pattern P_(A), P_(D), P_(C), P_(B).Fourth row 1136 indicates that pilot sequence 4 corresponds to a phaserotation of 2n and follows the pattern P_(A), P_(A), P_(A), P_(A).

FIGS. 10 and 11 are examples in which there are four pilot sequences andfour pilots per sequence. In other embodiments, there may be differentnumbers of alternative pilot sequences available for selection and/ordifferent numbers of pilots per sequence.

FIG. 12 is a drawing 1200 illustrating two examples in which a pilotsequence from the table 1102 of FIG. 11 is selected for transmission inan exemplary peer discovery resource set 902 described with respect toFIG. 9. Drawings 1202 and 1204 illustrate an example in whichalternative pilot sequence 1 of row 1130 is selected for transmission.In this example, drawing 1202 illustrates that there is a first uniformphase shift of 90 degrees, as indicated by box 1206, between successivepilot symbols in the sequence. Drawing 1204 illustrates that there is asecond uniform phase rotation of 22.5 degrees, as indicated by box 1208,which is a function of the first uniform phase rotation, introduced intodata symbols to be transmitted with regard to a reference constellation.The reference constellation used for the data symbols of the peerdiscovery resource set is, e.g., a QAM constellation, e.g., one of a QAM4, QAM 16, QAM 64 or QAM 256 constellation.

Drawings 1252 and 1254 illustrate an example in which alternative pilotsequence 2 of row 1132 is selected for transmission. In this example,drawing 1252 illustrates that there is a first uniform phase shift of180 degrees, as indicated by box 1256, between successive pilot symbolsin the sequence. Drawing 1254 illustrates that there is a second uniformphase rotation of 45 degrees, as indicated by box 1258, which is afunction of the first uniform phase rotation, introduced into datasymbols to be transmitted with regard to a reference constellation.

FIG. 13 is a drawing 1300 illustrating an example in which device 1 102of system 100 of FIG. 1 decides that it would like to transmit, e.g.,broadcast, peer discovery information, monitors a plurality of differentsets of peer discovery resources, and selects a peer discovery resourceand a peer discovery pilot sequence as a function of the monitoredinformation. Device 1 102 may implement a communications method inaccordance with flowchart 200 of FIG. 2 and/or be implemented inaccordance with device 300 of FIG. 3. Device 1 102 would like totransmit its discovery signals such as to be detectable by other devicesin its vicinity, while limiting its interference impact to thesuccessful communication of other peer discovery signaling already inprogress.

In the example of FIG. 13, devices (device 2 104, device 3 106, device 4108, device 5 110, device 6 112, device 7 114, . . . , device N 116)have each already selected a peer discovery resource set and a peerdiscovery pilot sequence and are transmitting generated peer discoverysignals including pilots symbols and data symbols. The pilot symbols arein accordance with the selected pilot sequence, and the pilot symbolsand the data symbols are communicated using the air link resources,e.g., set of OFDM tone-symbols, of the selected peer discovery resourceset.

Device 2 104 transmits its peer discovery signals 1302 in accordancewith device 2 selected peer discovery resource set 1304 and device 2selected peer discovery pilot sequence 1306. Device 3 106 transmits itspeer discovery signals 1308 in accordance with device 3 selected peerdiscovery resource set 1310 and device 3 selected peer discovery pilotsequence 1312. Device 4 108 transmits its peer discovery signals 1314 inaccordance with device 4 selected peer discovery resource set 1316 anddevice 4 selected peer discovery pilot sequence 1318. Device 5 110transmits its peer discovery signals 1320 in accordance with device 5selected peer discovery resource set 1322 and device 5 selected peerdiscovery pilot sequence 1324. Device 6 112 transmits its peer discoverysignals 1326 in accordance with device 6 selected peer discoveryresource set 1328 and device 6 selected peer discovery pilot sequence1330. Device 7 114 transmits its peer discovery signals 1332 inaccordance with device 7 selected peer discovery resource set 1334 anddevice 7 selected peer discovery pilot sequence 1336. Device N 116transmits its peer discovery signals 1338 in accordance with device Nselected peer discovery resource set 1340 and device N selected peerdiscovery pilot sequence 1342.

Some of the devices may have selected and may be using the same peerdiscovery resource set. For example, device 4 108 and device N 116 maybe concurrently using the same peer discovery resource set, e.g. withdifferent selected pilot sequences.

Device 1 102 monitors a plurality of different sets of peer discoverycommunications resources and receives signals (1302, 1308, 1314, 1320,1326, 1332, 1338), as indicated by the dashed line arrows. Device 1determines an amount of energy associated with at least a portion of theplurality of different sets of peer discovery resources and selects aset of communications resources to use for communication, e.g., a set ofcommunications resources to use for its transmission of its intendedpeer discovery signals. Device 1 102, also selects a peer discoverypilot sequence to use for its intended peer discovery signaling. In oneembodiment, device 1 102 makes a pseudo random selection of the pilotsequence to use. In another embodiment, device 1 102 selects the pilotsequence based on determined energy associated with different receivedpilot sequences corresponding to the selected peer discovery resourceset.

Device 1 102 generates and transmits pilot symbols and data symbols inaccordance with the selected pilot sequence. The transmission is overthe set of air link communications resources, e.g., set of contiguousOFDM tone-symbols, which correspond to the selected set ofcommunications resources which was selected by device 1 102.

FIG. 14 is a drawing 1400 illustrating exemplary wireless terminal 1measurements and operations corresponding to the FIG. 13 exemplaryscenario. Drawing 1400 includes table 1401 listing WT determined energylevels associated with different peer discovery resources and/ordifferent pilot sequences based on received signal measurements. Firstcolumn 1402 identifies the peer discovery resource set. Second column1404 lists WT 1 determined energy level for at least a first portion ofthe peer discovery resource set. Third column 1406 lists WT 1 determinedenergy attributable to signals for pilot sequence 1. Fourth column 1408lists WT 1 determined energy attributable to signals for pilot sequence2. Fifth column 1410 lists WT 1 determined energy attributable tosignals for pilot sequence 3. Sixth column 1412 lists WT 1 determinedenergy attributable to signals for pilot sequence 4.

First row 1414 lists that: the determined energy level for at least afirst portion of peer discovery resource set 1 is PWR_(PDRS1), the WT 1determined energy attributable to signals for pilot sequence 1corresponding to peer discovery resource set 1 is PWR_(Pilot(1,1)), theWT 1 determined energy attributable to signals for pilot sequence 2corresponding to peer discovery resource set 1 is PWR_(Pilot(1,2)), theWT 1 determined energy attributable to signals for pilot sequence 3corresponding to peer discovery resource set 1 is PWR_(Pilot(1,3)), andthe WT 1 determined energy attributable to signals for pilot sequence 4corresponding to peer discovery resource set 1 is PWR_(Pilot(1,4)).Second row 1416 lists that: the determined energy level for at least afirst portion of peer discovery resource set 2 is PWR_(PDRS2), the WT 1determined energy attributable to signals for pilot sequence 1corresponding to peer discovery resource set 2 is PWR_(Pilot(2,1)), theWT 1 determined energy attributable to signals for pilot sequence 2corresponding to peer discovery resource set 2 is PWR_(Pilot(2,2)), theWT 1 determined energy attributable to signals for pilot sequence 3corresponding to peer discovery resource set 2 is PWR_(Pilot(2,3)), andthe WT 1 determined energy attributable to signals for pilot sequence 4corresponding to peer discovery resource set 2 is PWR_(Pilot(2,4)).

Third row 1418 lists that: the determined energy level for at least afirst portion of peer discovery resource set 3 is PWR_(PDRS3), the WT 1determined energy attributable to signals for pilot sequence 1corresponding to peer discovery resource set 3 is PWR_(Pilot(3,1)), theWT 1 determined energy attributable to signals for pilot sequence 2corresponding to peer discovery resource set 3 is PWR_(Pilot(3,2)), theWT 1 determined energy attributable to signals for pilot sequence 3corresponding to peer discovery resource set 3 is PWR_(Pilot(3,3)), andthe WT 1 determined energy attributable to signals for pilot sequence 4corresponding to peer discovery resource set 3 is PWR_(Pilot(3,4)).Fourth row 1420 lists that: the determined energy level for at least afirst portion of peer discovery resource set 4 is PWR_(PDRS4), the WT 1determined energy attributable to signals for pilot sequence 1corresponding to peer discovery resource set 4 is PWR_(Pilot(4,1)), theWT 1 determined energy attributable to signals for pilot sequence 2corresponding to peer discovery resource set 4 is PWR_(Pilot(4,2)), theWT 1 determined energy attributable to signals for pilot sequence 3corresponding to peer discovery resource set 4 is PWR_(Pilot(4,3)), andthe WT 1 determined energy attributable to signals for pilot sequence 4corresponding to peer discovery resource set 4 is PWR_(Pilot(4,4)).Fourteenth Row 1422 lists that: the determined energy level for at leasta first portion of peer discovery resource set 14 is PWR_(PDRS14), theWT 1 determined energy attributable to signals for pilot sequence 1corresponding to peer discovery resource set 14 is PWR_(Pilot(14,1)),the WT 1 determined energy attributable to signals for pilot sequence 2corresponding to peer discovery resource set 14 is PWR_(Pilot(l4,2)),the WT 1 determined energy attributable to signals for pilot sequence 3corresponding to peer discovery resource set 14 is PWR_(Pilot(14,3)),and the WT 1 determined energy attributable to signals for pilotsequence 4 corresponding to peer discovery resource set 14 isPWR_(Pilot(14,4)).

In one embodiment column 1404 of table 1401 has been filled out bywireless terminal 1 based on measurements of received peer discoverysignals obtained from the monitoring of a plurality of different sets ofcommunications resources, e.g., in accordance with step 204 of flowchart200 of FIG. 2. In some embodiments the information of column 1404 isbased on received signals from resources, e.g., OFDM tone-symbols,designated as pilot symbol and data symbol resources. In someembodiments the information of column 1402 is based on received signalsfrom resources designated as pilot symbol resources but does not includeresources designated as data symbol resources. In some embodiments, theinformation of column 1404 is based on a full peer discovery resourceset, e.g., PWR_(PDRS1) is, in some embodiments, is based on signalsreceived over the full set of 16 OFDM tone-symbols corresponding toresource set 1.

In one embodiment column 1406, 1408, 1410 and 1412 of table 1401 hasbeen filled out by wireless terminal 1 based on the determinations ofenergy attributable to signals corresponding to different ones of saidplurality of different pilot sequences, e.g., in accordance with step210 of flowchart 200 of FIG. 2. The information of columns 1406, 1408,1410 and 1412 is based on received signals corresponding to designatedpilot symbol locations in the peer discovery resource sets. In addition,corresponding to an individual peer discovery resource set, wirelessterminal 1 has separated the received pilot symbol signals to obtainpower levels corresponding to each pilot sequence.

Box 1424 indicates that WT 1 selects a peer discovery resource set basedon the determined energy level information of column 1404. For example,WT 1 selects a peer discovery resource set to use for its transmissionof peer discovery signals based on the determined energy levelscorresponding to the 14 alternative resource sets. In one embodiment, WT1 selects the resource set which has the lowest energy level value. Inanother embodiment, WT 1 determines which of the peer discovery resourcesets have a determined energy level below a predetermined threshold, andthen WT 1 pseudo-randomly selects a peer discovery resource set to usefrom among those determined to be below the predetermined threshold. Box1424 may correspond to step 208 of flowchart 200 of FIG. 2.

Following selection of a peer discovery resource set, WT 1 selects apilot sequence to use for the selected peer discovery resource set, asindicated by box 1426. Box 1426 may correspond to step 212 of flowchart200 of FIG. 2. In some embodiments, WT 1 makes a pseudo-random selectionof one of the plurality of different pilot sequences, e.g., 1 of thefour alternative pilot sequences. This scenario is represented bysub-step 214 of flowchart 200 of FIG. 2. In another embodiment, WT 1selects one of the plurality of different pilot sequences based on thedetermined amount of energy attributable to the different individualones of the plurality of pilot sequences. This scenario is representedby sub-step 216 of flowchart 200 of FIG. 2. For example, consider thatWT 1 has selected to use peer discovery resource set 2, then WT 1selects the pilot sequence as a function of: PWR_(PILOT(2,1)),PWR_(PILOT(2,2)), PWR_(PILOT(2,3)), PWR_(PILOT(2,4)). In someembodiments, WT 1 selects the pilot sequence from among the fouralternatives which has the lowest amount of energy which is attributedto it. This scenario is represented by subset 218 of flowchart 200. Inanother embodiment, WT 1 selects the pilot sequence from among apredetermined number of the lowest energy level pilot sequences. Forexample, WT 1 pseudo-randomly selects the pilot sequence to use fromamong the two lowest power pilot sequences.

Following selection of the pilot sequence, WT 1 generates peer discoverysignals including pilot symbols and data symbols in accordance withselected pilot sequence, as indicated by box 1428. In some embodiments,the generated data symbols are a function of the pilot symbols, e.g.,with regard to phase. For example, consider that the embodiment usespilot sequences as described with respect to FIG. 11 and FIG. 12. Insuch a scenario, phase shift applied to data symbols is a function ofphase shift corresponding to pilot symbols.

The generated peer discovery signals including pilot symbols and datasymbols are transmitted using the selected peer discovery resource setas indicted by box 1430. Thus WT 1 102 of FIG. 13, which now has aselected peer discovery resource set and a selected pilot sequence,transmits its peer discovery signals.

FIG. 15 is a flowchart 1500 an exemplary method of operating acommunications device to communicate information in accordance with anexemplary embodiment. The exemplary communications device implementingthe method of flowchart 1500 is, e.g., one of the communications devicesof system 100 of FIG. 1. Operation starts in step 1502, where thecommunications device is powered on and initialized and proceeds to step1504. In step 1504, the communications device performs non-coherentmodulation to communicate coding information on pilot signals. Operationproceeds from step 1504 to step 1506. In step 1506 the communicationsdevice performs coherent modulation in a manner consistent with thecoding information communicated on the pilot signals to generate datasignals. Operation proceeds from step 1506 to step 1508. In step 1508the communications device transmit the pilot signals and data signal ondifferent sets of communications resources. Operation proceeds from step1508 to step 1504.

In some embodiment the coding information communicated in the pilotsignals includes information indicating one of a plurality of possiblecodes used to code data transmitted using the coherent modulation. Insome embodiments said plurality of possible codes correspond todifferent graphical structures. In some embodiments, the possible codesinclude multiple different LDPC codes. In some such embodiments, thedifferent LDPC codes correspond to different code graph structures.

In some embodiments, the coding information includes interleavinginformation, said interleaving information indicating one of a pluralityof different interleaving methods which may be used to interleave dataprior to transmission using said coherent modulation. In some exemplaryembodiments, coding before modulation is initially performed or codedmodulation is initially performed, e.g., via a convolution encoder, togenerate coded symbols from input data to be communicated. Then thegenerated coded symbols are interleaved using a specific selectedinterleaving method. In various embodiments the coding informationcommunicated on the pilot signals indicates the type of data transmittedusing the coherent modulation, different types of data being coded usingdifferent coding methods according to a predetermined relationshipbetween the type of data and the coding method used.

FIG. 16 is a drawing of an exemplary communications device 1600, inaccordance with an exemplary embodiment. Exemplary communications device1600 is, e.g., one of the wireless communications devices of FIG. 1.Exemplary communications device 1600 may, and sometimes does, implementa method in accordance with flowchart 1500 of FIG. 15.

Communications device 1600 includes a processor 1602 and memory 1604coupled together via a bus 1609 over which the various elements (1602,1604) may interchange data and information. Communications device 1600further includes an input module 1606 and an output module 1608 whichmay be coupled to processor 1602 as shown. However, in some embodiments,the input module 1606 and output module 1608 are located internal to theprocessor 1602. Input module 1606 can receive input signals. Inputmodule 1606 can, and in some embodiments does, include a wirelessreceiver and/or a wired or optical input interface for receiving input.Output module 1608 may include, and in some embodiments does include, awireless transmitter and/or a wired or optical output interface fortransmitting output.

Processor 1602 is configured to: perform non-coherent modulation tocommunicate coding information on pilot signals; perform coherentmodulation in a manner consistent with the coding informationcommunicated on the pilot signal to generated data signals; and transmitthe pilot signals and the data signals on different sets ofcommunications resources. In some embodiments, said coding informationcommunicated on the pilot signals includes information indicating one ofa plurality of possible codes used to code data transmitted using saidcoherent modulation. In some embodiments, the plurality of possiblecodes correspond to different graphical structures. In variousembodiments, said possible codes include multiple different LDPC codes.In some such embodiments, said different LDPC codes correspond todifferent code graph structures.

In some embodiments, said coding information includes interleavinginformation, said interleaving information indicating one of a pluralityof different interleaving methods which may be used to interleave dataprior to transmission using said coherent modulation. In some suchembodiments, said coding information communicated on the pilot signalsindicates the type of data transmitted using said coherent modulation,different types of data being coded using different coding methodsaccording to a predetermined relationship between the type of data andthe coding method used.

In some embodiments, said coding information indicates a combination ofa convolutional code and an interleaving pattern. In some embodiments,individual codes are identical or complementary convolutional codesfollowed by different or random or pseudo-random interleaving.

FIG. 17 is an assembly of modules 1700 which can, and in someembodiments is, used in the communications device 1600 illustrated inFIG. 16. The modules in the assembly 1600 can be implemented in hardwarewithin the processor 1602 of FIG. 16, e.g., as individual circuits.Alternatively, the modules may be implemented in software and stored inthe memory 1604 of the communications device 1600 shown in FIG. 16.While shown in the FIG. 16 embodiment as a single processor, e.g.,computer, it should be appreciated that the processor 1602 may beimplemented as one or more processors, e.g., computers. When implementedin software the modules include code, which when executed by theprocessor, configure the processor, e.g., computer, 1602 to implementthe function corresponding to the module. In some embodiments, processor1602 is configured to implement each of the modules of the assembly ofmodules 1600. In embodiments where the assembly of modules 1700 isstored in the memory 1604, the memory 1604 is a computer program productcomprising a computer readable medium comprising code, e.g., individualcode for each module, for causing at least one computer, e.g., processor1602, to implement the functions to which the modules correspond.

Completely hardware based or completely software based modules may beused. However, it should be appreciated that any combination of softwareand hardware (e.g., circuit implemented) modules may be used toimplement the functions. As should be appreciated, the modulesillustrated in FIG. 16 control and/or configure the communicationsdevice 1600 or elements therein such as the processor 1602, to performthe functions of the corresponding steps illustrated in the methodflowchart 1500 of FIG. 15.

FIG. 17 is an assembly of modules 1700 including a module 1704 forperforming non-coherent modulation to communicate coding information onpilot signals and a module 1706 for performing coherent modulation in amanner consistent with the coding information communicated on the pilotsignals to generate data signals. Assembly of modules 1700 furtherincludes a module 1708 for transmitting the pilot signals on differentsets of communications resources.

In some embodiments, said coding information communicated on the pilotsignals includes information indicating one of a plurality of possiblecodes used to code data transmitted using said coherent modulation. Insome embodiment said plurality of possible codes correspond to differentgraphical structures. In various embodiments, said possible codesinclude multiple different LDPC codes. In some such embodiments, saiddifferent LDPC codes correspond to different code graph structures. Insome embodiments, said coding information includes interleavinginformation, said interleaving information indicating one of a pluralityof different interleaving methods which may be used to interleave dataprior to transmission using said coherent modulation. In some suchembodiments, said coding information communicated on the pilot signalsindicates the type of data transmitted using said coherent modulation,different types of data being coded using different coding methodsaccording to a predetermined relationship between the type of data andthe coding method used.

In some embodiments, said coding information indicates a combination ofa convolutional code and an interleaving pattern. In some embodiments,individual codes are identical or complementary convolutional codesfollowed by different or random or pseudo-random interleaving.

FIG. 18 illustrates four examples of exemplary coding information thatmay be communicated via pilot signals and non-coherent modulation. Theexamples of FIG. 18 may be used by a device implementing a method inaccordance with flowchart 1500 of FIG. 15 and/or flowchart 1900 of FIG.19 and/or a device implemented in accordance with device 1600 of FIG. 16and/or in accordance with assembly of modules 1700 of FIG. 17.

Table 1802 of FIG. 18 illustrates example 1 in which the codinginformation to be communicated is one of a plurality of different LDPCcodes. First column 1804 indicates the coding information to becommunicated and second column 1806 indicates the pilot symbol sequence.If it is to be communicated that LDPC code 1 is used to code the datatransmitted using coherent modulation, then pilot symbol sequence 1 isused for the pilot signals. If it is to be communicated that LDPC code 2is used to code the data transmitted using coherent modulation, thenpilot symbol sequence 2 is used for the pilot signals. If it is to becommunicated that LDPC code 3 is used to code the data transmitted usingcoherent modulation, then pilot symbol sequence 3 is used for the pilotsignals. If it is to be communicated that LDPC code 4 is used to codethe data transmitted using coherent modulation, then pilot symbolsequence 4 is used for the pilot signals. FIG. 10 illustrates an exampleof four different exemplary pilot sequences that are used in someembodiments, e.g., some embodiments, where there are 4 pilot symbolscommunicated in a pilot sequence.

Table 1808 of FIG. 18 illustrates example 2 in which the codinginformation to be communicated is one of a plurality of different codegraph structures. First column 1810 indicates the coding information tobe communicated and second column 1812 indicates the pilot symbolsequence. If it is to be communicated that code graph structure 1 isused to code the data transmitted using coherent modulation, then pilotsymbol sequence 1 is used for the pilot signals. If it is to becommunicated that code graph structure 2 is used to code the datatransmitted using coherent modulation, then pilot symbol sequence 2 isused for the pilot signals. If it is to be communicated that code graphstructure 3 is used to code the data transmitted using coherentmodulation, then pilot symbol sequence 3 is used for the pilot signals.If it is to be communicated that code graph structure 4 is used to codethe data transmitted using coherent modulation, then pilot symbolsequence 4 is used for the pilot signals.

Table 1814 of FIG. 18 illustrates example 3 in which the codinginformation to be communicated is one of a plurality of differentinterleaving methods. First column 1816 indicates the coding informationto be communicated and second column 1818 indicates the pilot symbolsequence. If it is to be communicated that interleaving method 1 is usedto code the data transmitted using coherent modulation, then pilotsymbol sequence 1 is used for the pilot signals. If it is to becommunicated that interleaving method 2 is used to code the datatransmitted using coherent modulation, then pilot symbol sequence 2 isused for the pilot signals. If it is to be communicated thatinterleaving method 3 is used to code the data transmitted usingcoherent modulation, then pilot symbol sequence 3 is used for the pilotsignals. If it is to be communicated that interleaving method 4 is usedto code the data transmitted using coherent modulation, then pilotsymbol sequence 4 is used for the pilot signals.

Table 1820 of FIG. 18 illustrates example 4 in which the codinginformation to be communicated is one of a plurality of different codingmethods, each of the different coding methods associated with differentdata types. First column 1822 indicates the data type to becommunicated; second column 1824 indicates the coding method to becommunicated; and third column 1826 indicates the pilot symbol sequence.If it is to be communicated that coding method 1 is used to code datatype 1 data which is transmitted using coherent modulation, then pilotsymbol sequence 1 is used for the pilot signals. If it is to becommunicated that coding method 2 is used to code data type 2 data whichis transmitted using coherent modulation, then pilot symbol sequence 2is used for the pilot signals. If it is to be communicated that codingmethod 3 is used to code data type 3 data transmitted using coherentmodulation, then pilot symbol sequence 3 is used for the pilot signals.If it is to be communicated that coding method 4 is used to code datatype 4 data which is transmitted using coherent modulation, then pilotsymbol sequence 4 is used for the pilot signals.

FIG. 19 is a flowchart 1900 of an exemplary method of operating acommunications device to communicate information, e.g., communicate peerdiscovery information, in accordance with an exemplary embodiment. Thecommunications device implementing the method of flowchart 1900 is,e.g., a wireless communications device which is part of a peer to peernetwork such as system 100 of FIG. 1. Operation starts in step 1902where the communications device is powered on and initialized. Operationproceeds from start step 1902 to steps 1904 and 1906, which may beperformed in parallel or serially.

In step 1904 the communications device performs non-coherent modulationto communicate coding information on pilot signals. Coding information1903 is an input to step 1904. Coding information 1903 includes, e.g.,one or more of LDPC code type, code graph structure identificationinformation, interleaving method identification information, data typeinformation, and coding method identification information.

In some embodiments, step 1904 includes one or more of sub-steps 1906,1908 and 1910. In sub-step 1906 the communications device determines apilot sequence as a function of the coding information 1903. Then insub-step 1908 the communications device generates pilot signals inaccordance with the determined pilot sequence. Operation proceeds fromsub-step 1908 to sub-step 1910, in which the communications deviceidentifies a first set of communications resources to carry thegenerated pilot signals.

Returning to step 1906, in step 1906 the communications device performscoherent modulation in a manner consistent with the coding informationcommunicated on the pilot signals to generate data signals. Codinginformation 1903 and data to be communicated 1905 are inputs to step1905. In some embodiments, the data to be communicated is peer discoveryinformation, e.g., one or more of a device identifier, a useridentifier, a group identifier, a service offered, a product offered, aservice request, a product request, a search input, a proximityindicator, a status indicator, etc.

In some embodiments, step 1906 includes one or more of sub-steps 1912and 1914. In sub-step 1912 the communications device encodes and/ormodulates the data to be communicated 1905, into a set of data signalsin accordance with the coding information 1903, said encoding and/ormodulating generating said set of data signals. Operation proceeds fromsub-step 1912 to sub-step 1914. In sub-step 1914 the communicationsdevice identifies a second set of communications resources to carry thegenerated data signals.

Operation proceeds from step 1904 and 1906 to step 1916. In step 1916the communications device transmits the pilot symbols and data symbolson different sets of communications resources. In some embodiments, thecoding information communicated on the pilot signals indicates one or aplurality of possible codes used to code data transmitted using saidcoherent modulation. In some embodiments, said plurality of possiblecodes correspond to different graphical structures. In some suchembodiments, the possible codes include multiple different LDPC codes.In some such embodiments, the different LDPC codes correspond todifferent code graph structures. In various embodiments the codinginformation includes interleaving information, said interleavinginformation indicating one of a plurality of different interleavingmethods which may be used to interleave data prior to transmission usingsaid coherent modulation. In some embodiments, the coding informationcommunicated on the pilot signals indicates the type of data transmittedusing said coherent modulation, different types of data being codedusing different coding methods according to a predetermined relationshipbetween the type of data and the coding method used.

Some examples of different types of data include, e.g., control data,voice data, image data, and text data. Some other examples of differenttypes of data include data classified by priority, data classified byservice level, data classified by latency consideration, etc. Otherexamples of different types of data include data classified byapplication. Still another example of different types of data includedifferent size block of data to be communicated prior to encoding.Different coding methods include, e.g., different coding rates,different constellations, different QAM levels, e.g., QAM 4 vs QAM 16,different levels of error correction, different codes of the same type,different types of codes, etc. Operation proceeds from step 1916 to theinputs of step 1904 and 1906, e.g., to process another set of codinginformation and data to be communicated.

FIG. 20 is a drawing 2000 illustrating an exemplary peer discoveryresource set 2002 used to carry pilot and data symbols. Peer discoveryresource set 2002 is, e.g., peer discovery resource set 804 of FIG. 8,where K=16 and K_(P)=4. Exemplary peer discovery resource set 2002includes 16 indexed OFDM tone-symbols (tone-symbol 1 2004, tone symbol 22006, tone-symbol 3 2008, tone-symbol 4 2010, tone-symbol 5 2012,tone-symbol 6 2014, tone-symbol 7 2016, tone-symbol 8 2018, tone-symbol9 2020, tone-symbol 10 2022, tone-symbol 11 2024, tone-symbol 12 2026,tone-symbol 13 2028, tone-symbol 14 2030, tone-symbol 15 2032 andtone-symbol 16 2034).

Diagonal line shading as indicated by box 2038 of legend 2036 indicatesthat an OFDM tone-symbol of the peer discovery resource set is used tocarry a pilot symbol, the set of pilot symbols conveying codinginformation by non-coherent modulation. Horizontal line shading asindicated by box 2040 of legend 2036 indicates that an OFDM tone-symbolof the peer discovery resource set is used to carry a data symbol, theset of data symbols conveying peer discovery data by a coherentmodulation scheme in accordance with the coding information conveyed bythe pilots. In this example a first subset of tone-symbols (2006, 2014,2022 and 2030) are designated to be used to carry pilot symbols, while asecond non-overlapping subset of tone-symbols (2004, 2008, 2010, 2012,2016, 2018, 2020, 2024, 2026, 2028, 2032, 2034) are used to carry thedata symbols. In the example of FIG. 20, tone-symbols (2006, 2014, 2022and 2030) carry pilot symbols (P1 2044, P2 2052, P3 2060 and P4 2068),respectively. In the example of FIG. 20, tone-symbols (2004, 2008, 2010,2012, 2016, 2018, 2020, 2024, 2026, 2028, 2032, 2034) carry data symbols(D1 2042, D2 2046, D3 2048, D4 2050, D5 2054, D6 2056, D7 2058, D8 2062,D9 2064, D10 2066, D11 2070, D12 2072), respectively.

Consider one example, in which the coding information to be communicatedis one of a plurality of different LDPC codes, e.g., as one or the codesof example 1 of table 1802 of FIG. 18. Further consider that the pilotsymbol sequences are represented by FIG. 10. Also consider that theresources to be used to carry the pilot signals and data signals are aset of peer discovery communications resources, e.g., peer discoveryresource set 2002. Further consider that the data to be communicated isa device identifier corresponding to a group, e.g., ID_(G1).

Consider that the coding information indicates LDPC code 3 is to beused. Table 1802 indicates that LDPC code 3 maps to pilot sequence 3.Pilot sequence 3 is defined as P1=+, P2=−, P3=+, P4=−, so thecommunications device generates those pilot symbols for communicationover OFDM tone-symbols (2006, 2014, 2022, 2030) respectively. Inaddition the communications device uses LDPC code 3 to process the inputdata to be communicated, e.g., the device identifier corresponding to agroup (ID_(G1)), to generate a set of QAM modulation symbols (D1, D2,D3, D4, D5, D5, D7, D8, D9, D10, D11, D12) which will communicate thedata by coherent modulation. The communications device transmits thepilot signals, e.g., pilot symbols, and data signals, e.g., datasymbols, on different sets of communications resources within the peerdiscovery resource set 2002.

FIG. 21 is a flowchart 2100 of an exemplary method of operating acommunications device, e.g., a wireless terminal, to recover informationcommunicated by first and second communications devices using a set ofcommunications resources. In some embodiments the set of communicationsresources are peer identification resources in an ad hoc network whichsupports peer to peer communications. In one example, the communicationsdevice implementing the method of flowchart 2100, the firstcommunications device and the second communications device are any ofthe peer to peer communications devices of system 100 of FIG. 1.Operation starts in step 2102, where the communications device ispowered on and initialized and proceeds to step 2104.

In step 2104 the communications device performs non-coherentdemodulation on pilot signals received on a first subset of said set ofcommunications resources to recover coding information. In someembodiments the recovered coding information includes informationindicating a first code used to encode data transmitted by said firstcommunications device and information indicating a second code used toencode data transmitted by said second communications device. In somesuch embodiments, the first and second codes are different. In someembodiments, the first and second codes correspond to differentgraphical structures. In some such embodiments, the first and secondcodes are different LDPC codes which use different LDPC code graphs.

In some embodiments, the recovered coding information includesinformation indicating a first interleaving operation which wasperformed by the first communications device on data to be transmittedprior to transmission and information indicating a second interleavingoperation which was performed by the second communications device ondata to be transmitted by the second communications device prior totransmission. In some such embodiments, the first and secondinterleaving operations perform different reordering operations.

In some embodiments, the recovered coding information includesinformation indicating a first code to be used to encode data to betransmitted by the first communications device and informationindicating a second code used to encode data transmitted by the secondcommunications device and also indicates different interleavingoperations performed by said first and second communications devicesprior to transmission of data by said first and second communicationsdevices, respectively.

In some embodiments, the non-coherent demodulation also providesinformation indicating whether a peer identifier communicated by atleast one of said first and second communications devices using coherentmodulation is a public identifier or a private identifier. Operationproceeds from step 2104 to step 2106.

In step 2106 the communications device generates first and secondchannel estimates from the pilot signals received on the first subset ofsaid communications resources, the first channel estimate correspondingto a communications channel corresponding to the first communicationsdevice, the second channel estimate corresponding to the secondcommunications device. Operation proceeds from step 2106 to step 2108.

In step 2108 the communications device performs coherent demodulation ondata signals received on a second subset of said set of communicationsresources using said first and said second channel estimates and saidcoding information communicated by said first communications device andto recover separate information communicated by said secondcommunications device. In various embodiments, the first subset issmaller than the second subset, and the first and second subsets arenon-overlapping. In some embodiments, signals received from both thefirst and second communications devices are received on at least some ofthe same resources in the first subset of resources and at least some ofthe same resources in the second subset of resource. In someembodiments, the information recovered using coherent demodulationincludes peer identifiers. In some embodiments the information recoveredfrom a device using coherent demodulation conveys at least one of a peerdevice identifier, a peer user identifier, a group identifier, a serviceoffered, a service requested, an item offered, an item requested,proximity information, and status information. In some embodiments,information recovered from the first and second device may be, andsometimes are, different types of information, e.g., different types ofpeer discovery information. Operation proceeds from step 2108 to step2104, e.g., where the communications device starts to process anotherset of received signals including pilots signals and data signals.

FIG. 22 is a drawing of an exemplary communications device 2200, e.g., awireless terminal, in accordance with an exemplary embodiment. Exemplarycommunications device 2200 is, e.g., one of the wireless communicationsdevices of FIG. 1. Exemplary communications device 2200 may, andsometimes does, implement a method in accordance with flowchart 2100 ofFIG. 21.

Communications device 2200 includes a processor 2202 and memory 2204coupled together via a bus 2209 over which the various elements (2202,2204) may interchange data and information. Communications device 2200further includes an input module 2206 and an output module 2208 whichmay be coupled to processor 2202 as shown. However, in some embodiments,the input module 2206 and output module 2208 are located internal to theprocessor 2202. Input module 2206 can receive input signals. Inputmodule 2206 can, and in some embodiments does, include a wirelessreceiver and/or a wired or optical input interface for receiving input.Output module 2208 may include, and in some embodiments does include, awireless transmitter and/or a wired or optical output interface fortransmitting output.

Processor 2202 is configured to: perform non-coherent demodulation onpilot signals received on a first subset of said set of communicationsresources to recover coding information; and generate first and secondchannel estimates from the pilot signals received on the first subset ofsaid communications resources, the first channel estimate correspondingto a communications channel corresponding to a first communicationsdevice, the second channel estimate corresponding to a secondcommunications device. Processor 2202 is further configured to performcoherent demodulation on data signals received on a second subset ofsaid set of communications resources using said first and second channelestimates and said coding information to recover informationcommunicated by said first communications device and to recover separateinformation communicated by said second communications device. In someembodiments, said recovered coding information includes informationindicating a first code used to encode data transmitted by said firstcommunications device and information indicating a second code used toencode data transmitted by said second communications device. In someembodiments, the first and second codes are different. In someembodiments, the first and second codes correspond to differentgraphical structures. In some such embodiments, the first and secondcodes are different LDPC codes which use different LDPC code graphs.

In some embodiments, said recovered coding information includesinformation indicating a first interleaving operation which wasperformed by the first communications device on data to be transmittedprior to transmission and information indicating a second interleavingoperation which was performed by the second communications device ondata to be transmitted by the second communications device prior totransmission. In some such embodiments, said first and secondinterleaving operations perform different data reordering operations.

In various embodiments, said recovered coding information includesinformation indicating a first code used to encode data transmitted bysaid first communications device and information indicating a secondcode used to encode data transmitted by said second communicationsdevice and also indicates different interleaving operations performed bysaid first and second communications devices prior to transmission ofdata by said first and second communications devices, respectively.

In some embodiments, the first subset is smaller than said secondsubset, said first and second subsets being non-overlapping. In somesuch embodiments, signals from both the first and second communicationsdevices are received on at least some of the same resources in the firstsubset of resources and at least some of the same resources in thesecond subset of resources.

In some embodiments, the set of communications resources are peeridentification resources in an ad hoc network which supports peer topeer communications. In some such embodiments, the information recoveredusing coherent demodulation includes peer identifiers.

In some embodiments, said non-coherent demodulation also providesinformation indicating whether said peer identifier communicated by atleast one of said first and second communications device using coherentmodulation is a public identifier or a private identifier.

FIG. 23 is an assembly of modules 2300 which can, and in someembodiments is, used in the communications device 2200, e.g., wirelessterminal, illustrated in FIG. 22. The modules in the assembly 2300 canbe implemented in hardware within the processor 2202 of FIG. 22, e.g.,as individual circuits. Alternatively, the modules may be implemented insoftware and stored in the memory 2204 of the communications device 2200shown in FIG. 22. While shown in the FIG. 22 embodiment as a singleprocessor, e.g., computer, it should be appreciated that the processor2202 may be implemented as one or more processors, e.g., computers. Whenimplemented in software the modules include code, which when executed bythe processor, configure the processor, e.g., computer, 2202 toimplement the function corresponding to the module. In some embodiments,processor 2202 is configured to implement each of the modules of theassembly of modules 2300. In embodiments where the assembly of modules2300 is stored in the memory 2204, the memory 2204 is a computer programproduct comprising a computer readable medium comprising code, e.g.,individual code for each module, for causing at least one computer,e.g., processor 2202, to implement the functions to which the modulescorrespond.

Completely hardware based or completely software based modules may beused. However, it should be appreciated that any combination of softwareand hardware (e.g., circuit implemented) modules may be used toimplement the functions. As should be appreciated, the modulesillustrated in FIG. 4 control and/or configure the communications device2200 or elements therein such as the processor 2202, to perform thefunctions of the corresponding steps illustrated in the method flowchart2100 of FIG. 21.

Assembly of module 2300 includes a module 2304 for performingnon-coherent demodulation on pilot signals received on a first subset ofa set of communications resources to recover coding information and amodule 2306 for generating first and second channel estimates from thepilot signals received on said first subset of said communicationsresources, the first channel estimate corresponding to communicationschannel corresponding to a first communications device, the secondchannel estimate corresponding to a second communications device.Assembly of modules 2300 further includes a module 2308 for performingcoherent demodulation on data signals received on a second subset ofsaid set of communications resources using said first and said secondchannel estimates and said coding information to recover informationcommunicated by said first communications device and to recover separateinformation communicated by said second communications device.

In some embodiments, said recovered coding information includesinformation indicating a first code used to encode data transmitted bysaid first communications device and information indicating a secondcode used to encode data transmitted by said second communicationsdevice. In some embodiments, the first and second codes are different.In some embodiments, the first and second codes correspond to differentgraphical structures. In some such embodiments, the first and secondcodes are different LDPC codes which use different LDPC code graphs.

In some embodiments, said recovered coding information includesinformation indicating a first interleaving operation which wasperformed by the first communications device on data to be transmittedprior to transmission and information indicating a second interleavingoperation which was be performed by the second communications device ondata to be transmitted by the second communications device prior totransmission. In some such embodiments, said first and secondinterleaving operations perform different data reordering operations.

In various embodiments, said recovered coding information includesinformation indicating a first code used to encode data transmitted bysaid first communications device and information indicating a secondcode used to encode data transmitted by said second communicationsdevice and also indicates different interleaving operations performed bysaid first and second communications devices prior to transmission ofdata by said first and second communications devices, respectively.

In some embodiments, the first subset is smaller than said secondsubset, said first and second subsets being non-overlapping. In somesuch embodiments, signals from both the first and second communicationsdevices are received on at least some of the same resources in the firstsubset of resources and at least some of the same resources in thesecond subset of resources.

In some embodiments, the set of communications resources are peeridentification resources in an ad hoc network which supports peer topeer communications. In some such embodiments, the information recoveredusing coherent demodulation includes peer identifiers.

In some embodiments, said non-coherent demodulation also providesinformation indicating whether said peer identifier communicated by atleast one of said first and second communications device using coherentmodulation is a public identifier or a private identifier.

FIG. 24 is a drawing 2400 illustrating an example in which a wirelesscommunications device, e.g., a wireless terminal, recovers informationcommunicated by two other wireless communications devices using a set ofcommunications resources in accordance with an exemplary embodiment.Drawing 2400 includes exemplary communications devices (wirelessterminal 1 2402, wireless terminal 2 2404, wireless terminal 3 2406).The wireless terminals (2402, 2404, 2406) are, e.g., any of theexemplary devices of system 100 of FIG. 1. Wireless terminal 1 2402 is,e.g., a wireless terminal implementing a method in accordance withflowchart 2100 of FIG. 21. Wireless terminal 2 2404 and wirelessterminal 3 2406 are, e.g., wireless terminals implementing a method inaccordance with flowchart 1500 of FIG. 15 and/or flowchart 1900 of FIG.19. Wireless terminal 1 2402 includes a non-coherent demodulation module2438, a channel estimation module 2440 and a coherent demodulationmodule 2442. Modules (2438, 2440, 2442) are, in some embodiments,modules (2304, 2306, 2308) of assembly of modules 2300 of FIG. 23.

Wireless terminal 2 2404 has data 2 2408 that it would like tocommunicate over a peer discovery resource set. WT 2 2404 is currentlyusing peer discovery resource set 1 2422. Wireless terminal 2 2404 isusing code 4 2410 to code and/or modulate data 2 2408 into a set of datamodulation symbols. Coherent modulation will be used to communicate thedata symbols. Code 4 2410 maps to pilot sequence 4 2412, e.g., inaccordance with a predetermined mapping known to WTs (2402, 2404, 2406).Code 4 2410 will be communicated via non-coherent modulation using pilotsequence 4 2412 from among a predetermined set of different alternativepilot sequences. Wireless terminal 2 2404 generates and transmits peerdiscovery signal 2 2420 over peer discovery air link resource set 2422.Drawing 2424 represents the composite of the peer discovery signal 22420 and air link resource set 1 2422. Peer discovery signal 2 2420includes 12 data modulation symbols (D1 ₂, D2 ₂, D3 ₂, D4 ₂, D5 ₂, D6 ₂,D7 ₂, D8 ₂, D9 ₂, D10 ₂, D11 ₂, D12 ₂) and pilot sequence 4 (+−+−)mapped to the 16 ordered OFDM tone-symbols as shown in 2424. Peerdiscovery signal 2 2420 is communicated from wireless terminal 2 2404 towireless terminal 1 2402 using peer discovery air link resource set 12422, and the channel between WT 2 2404 and WT 1 2402 is represented byh(2,1) 2426.

Wireless terminal 3 2406 has data 3 2414 that it would like tocommunicate over a peer discovery resource set. WT 3 2406 is currentlyusing peer discovery resource set 1 2422. Note that peer discoveryresource set 1 2422 is being used concurrently by both WT 2 2404 and WT3 2406. Wireless terminal 3 2406 is using code 1 2416 to code and/ormodulate data 3 2414 into a set of data modulation symbols. Coherentmodulation will be used to communicate the data symbols. Code 1 2416maps to pilot sequence 1 2418, e.g., in accordance with a predeterminedmapping known to WTs (2402, 2404, 2406). Code 1 2416 will becommunicated via non-coherent modulation using pilot sequence 1 2418from among a predetermined set of different alternative pilot sequences.Wireless terminal 3 2406 generates and transmits peer discovery signal 32428 over peer discovery air link resource set 2422. Drawing 2430represents the composite of the peer discovery signal 3 2428 and airlink resource set 1 2422. Peer discovery signal 3 2428 includes 12 datamodulation symbols (D1 ₃, D2 ₃, D3 ₃, D4 ₃, D5 ₃, D6 ₃, D7 ₃, D8 ₃, D9₃, D10 ₃, D11 ₃, D12 ₃) and pilot sequence 1 (++++) mapped to the 16ordered OFDM tone-symbols as shown in 2430. Peer discovery signal 3 2428is communicated from wireless terminal 3 2406 to wireless terminal 12402 using peer discovery air link resource set 1 2422, and the channelbetween WT 3 2406 and WT 1 2402 is represented by h(3,1) 2432.

Wireless terminal 1 2402 receives signals 2433 corresponding to air linkresource set 2422. Signals 2433 represents a composite of transmittedsignals (2420 and 2420), subject to communications channels (h(2,1)2426,h(3,1) 2432), respectively. Received signals 2433 includes receivedpilots signals 2434 and received data signals 2436. Received pilotsignals 2433 corresponds to the received signals over the air linkresources carrying the pilot symbols, e.g., the four pilot OFDMtone-symbols in peer discovery resource set 1 2422. Received datasignals 2436 corresponds to the received signals over the air linkresources carrying the data modulation symbols, e.g., the twelve dataOFDM tone-symbols, in peer discovery resource set 1 2422.

Non-coherent demodulation module 2438 processes the received pilotsignals 2434 and identifies that pilot sequence 4 has been detected asindicated by box 2444. WT 1 2402 further identifies, e.g., from storedinformation associating different pilot sequences with different codinginformation, that code 4 was used for coding and/or modulating the datacommunicated on the data symbols from the same device that transmittedpilot symbol sequence 4, as indicated by box 2446. Non-coherentdemodulation module 2438, in processing the received pilot signals 2434also identifies that pilot sequence 1 has been detected as indicated bybox 2448. WT 1 2402 further identifies, e.g., from stored informationassociating different pilot sequences with different coding information,that code 1 was used for coding and/or modulating the data communicatedon the data symbols from the same device that transmitted pilot symbolsequence 1, as indicated by box 2450.

Channel estimation module 2440 uses the received pilot signals 2434 toestimate two channels. Corresponding to pilot sequence 4, channelestimation module 2440 generates estimated h(2,1) 2452. Corresponding topilot sequence 1, channel estimation module 2440 generates estimatedh(3,1) 2454.

Coherent demodulation module 2442 performs coherent demodulation on thereceived data signals 2436, using the estimated channels (estimated(h2,1) 2452, estimated (h3,1) 2454) and the identified codes (code 42456, code 1 2458), to recover information communicated by the seconddevice (recovered data 2 2456) and information communicated by the thirddevice (recovered data 3 2458). Consider that the recovery issuccessful; recovered data 2 2456 matches data 2 2408, and recovereddata 3 2458 matches data 3 2414.

Various aspects and features of some embodiments will be described. Someaspects are related to methods and apparatus for choosing andmaintaining pilot phase in a peer to peer network. In some embodiments apilot phase is embedded in a small codeword, which typically spans thepilot positions of the peer discovery signals. This codeword is decodednon-coherently by any receiver to retrieve the pilot phase, which willbe further used to decode the peer discovery codeword. Various aspectsare directed to simple methods for a peer to peer device to choose apilot phase.

In some embodiments each pilot phase corresponds to a different(non-coherent) codeword. There are two simple codebooks which can be,and sometimes are, used for this purpose, one is Walsh sequence and theother is Fourier sequence. Various exemplary methods are not necessarilybinded to a particular choice of the codebook. Other codebooks may be,and sometimes are, used in various exemplary embodiments. However, forsimplicity of explanation, these two exemplary codebooks, Walsh sequenceand Fourier sequence types, are used in exemplary presented examples.

Examples will now be described with regard to one exemplary peer to peernetwork. After a device joins the network, the device will first try tofind a resource, named as PDRID (peer discovery resource ID) tobroadcast its identity. Various methods may be used for picking the ID.One simple approach is to pick the PDRID with the least detected energyon it. After that, the device also has to pick the pilot phase. Thereare possibly multiple other peers using the same PDRID. The device willdecode the (possibly multiple) pilot phases being used by said otherpeers and pick one from the rest available pilot phases. In an examplewhere Walsh sequences are being used for pilot phase codewords, thedevice, in some embodiments, carries out FHT (fast hadamard transform)to get an estimate of energy on each of the possible pilot phases. Ingeneral, the device will try to non-coherently decode the pilot phasesin use and measure their energy.

After obtaining the energy associated with each pilot phase, the devicecan make a decision on which pilot phase it will use. One possibility isto pick the one with the smallest energy on it. However, in somescenarios, for example, when Walsh sequence type of codewords are beingused, the protection is not the same between different pairs ofcodewords. For example, (1 1 1 1 1 1 1 1) is more likely to be confusedto be (1 1 1 1-1-1-1-1) rather than (1-1 1-1 1-1 1-1). In this case, adevice, in some embodiments, will pick some codewords with higherpriorities than others, if all of them are available.

After successfully obtaining the pilot phase, in some embodiments, adevice will keep silent in his resource, during at least some times, tomonitor the current pilot phase usage. In the example of Walsh sequence,a device does FHT when it keeps silent and makes a decision if it has tochange its pilot phase choice and/or its PDRID.

Various aspects related to methods for hierarchical signaling in a peerto peer wireless network will be described. In wireless networks, it isoften desirable to organize coded information in a hierarchical manner.A simple example is when the set of available symbols (or physicalresources) is divided into (i) the support of a small code (or of apilot sequence) and (ii) the support set of a larger code (carrying thedata). As we will see, this layered coding is of particular interestwhen one aims at decoding/detecting several peers interfering on thesame physical link. Various aspects include encapsulating someinformation characterizing the transmitted coherent (typically large)codebook (ii) into a non-coherent pilot (typically small) codebooklocated in (i). At the receiving device (RX), the non-coherent code isused for channel estimation as well as for obtaining informationcharacterizing the coherent code. This hierarchical decoding isparticularly efficient to deal with several interferers, e.g., incombination with joint iterative decoding of the coherent code. It couldalso be, and in some embodiments is, used in the non-interference caseto characterize which coding/decoding is being used (e.g., decoding inpeer discovery performed via matching or Viterbi).

A first example will now be described. In peer to peer and wirelessnetworks, a key feature, in some embodiments, is the ability ofdetecting and decoding several peers interfering on a same physicalresource. First, several strategies can be devised at a system level inorder to efficiently use the available but limited air interfaceresources. Second, to complement the first approach, it is desirablethat each receiving device (RX) detects and decodes jointly differentpeers on a same link. This is a multi-user interference channel where,in practice, the state of the various physical links is unknown. The RXhas to non-coherently decode several interferers; a task that is quitecomplex in general. It is therefore advantageous, in accordance withsome embodiments, to split this complex non-coherent coding task intotwo simple tasks: (i) non-coherent coding for a fraction of the symbols;(ii) standard coherent coding for the remaining symbols. In other words,coding is performed in a hierarchical manner (where typically two stagesare considered). The (typically small and low rate) non-coherent codeis, in some embodiments, supported by a set of symbols that can beviewed as “pilots,” hence the name of “pilot code.” The second(typically larger) code will be referred to as coherent code.

A first consequence of this hierarchical coding scheme is that the RX,in some embodiments, uses this non-coherent pilot code to jointlyestimate the channels formed by the interfering links A secondconsequence, in some embodiments, is that, because each TX uses aparticular non-coherent pilot codeword, the RX will get some informationrelative to each of the TX codebooks, which it can further use to decodethe second (typically large) coherent code. The hierarchical coding isparticularly well-adapted to the problem of joint decoding in a wirelessnetwork where each node broadcasts synchronously certain information. Animportant feature of some embodiments is that the non-coherent pilotcode, in some embodiments, communicates information on the particularcoherent codebook used by the TX. This idea is particularly suitable forthe case of multi-user detection because it reduces the originalnon-coherent multi-user decoding problem into a similar problem butusing much shorter (pilot) codes. Codebook characteristics that can beencoded in the pilot codes are, e.g., connectivity for sparse graphcodes, constraint length or polynomials for convolutional codes,bit/symbol permutation etc.

A second example will now be described. An example, where hierarchicalcoding is of interest, are some peer to peer networks including a timingstructure including peer discovery. In some peer to peer networks,during a peer discovery phase, each device broadcasts its particular ID.This ID can be of different kinds Consider an example where there aretwo types: public or private. Public IDs are encoded via a convolutionalcode. Private IDs do not need to be encoded because compatible privateIDs form a small set of random sequences, which by default is already agood low rate code. A possibility is to encode the type of ID via anon-coherent pilot code. Then, the TX will first perform non-coherentdecoding, then, depending on the type, will perform either convolutionalcode decoding (via Viterbi or other algorithms) in the case of public IDor much faster sequence matching in the case of private ID. In addition,unequal error protection (e.g., for the format bits) can be addressed.

Methods and apparatus for orthogonalizing pilot sequences in a wirelessnetwork with many broadcasting nodes will be described. In some peer topeer and wireless networks, a key feature is the ability of detectingand decoding several peers interfering on a same physical resource. Atthe link level, this translates into the non-coherent joint decoding oftwo or more peers. In some embodiment, first, a subset of the time slotsis reserved for a non-coherent pilot code; second, the complementary setis associated with a coherent code. The coherent code is typically alarger code than the non-coherent pilot code. At the RX, thenon-coherent code is decoded in a first phase, during which the channelis also jointly estimated, and information is obtained that mayfacilitate or improve the decoding of the second coherent code. Considerthe case where several peers interfere in the same physical resource.One can consider the non-coherent code, whose positions form a typicallysmall subset of the available time slots, as a set of possible pilotsequences that interfere with each other. Various embodiments arerelated to a design of pilot codes, i.e., a set of pilot sequences, thatperform efficiently in scenarios of interest.

An example including peer discovery as part of an exemplary peer to peernetwork will now be described. Interfering signals arrive on a singletone. Consider a case of a static channel model:

y_(y) = h₁x_(t)^([1]) + h₂x_(t)^([2]) + v_(t)${h_{i} = {\sqrt{E_{i}}^{{j\theta}_{i}}}},{\theta_{i} \in {u\left( {0,{2\pi}} \right)}}$x_(t)^([i]) ∈ _(QPSK) or v_(t) ∈ (0, σ²)

Then, consider that 8 pilot positions are reserved for the pilot code,we can use 8 orthogonal Wash sequences to form the pilot code. In thetwo-interferer case, the probability of collision is 1/8 and this simplescheme performs very well in combination with joint iterative decoding.

Another example including peer discovery as part of an exemplary peer topeer network will now be described. Interfering signals arrive on asingle tone. Consider the case of a time-varying channel model whereeach signal experiences a different frequency offset. For example, atypically moderate offset, i.e., in a range of 400 Hz for peer discoveryin one exemplary system may be used.

New Channel Model: y_(t)=h_(t) ^([1])x_(t) ^([1])+h_(t) ^([2])x_(t)^([2])+v_(t)

where h_(t) ^([i])√{square root over (E_(i))}e^(j) ^(θ) ^(i)e^(j2πfit),f_(i)ε

( . . . 200, 200)

Then, consider that 12 pilot positions are reserved for the pilot code,we can use 8 specific “orthogonal” sequences to form the pilot code. Wewill describe potential sets of such sequences in the sequel. Noticefirst that they will play the rule of the Walsh sequence in the previousexample but now for a particular time-varying channel, which is a verygood first order approximation of the channel for peer discovery in anexemplary system.

The main task of the non-coherent channel decoder is to separate the twodifferent frequency offsets f1 and f2. Therefore, it is beneficial ifthe “orthogonal” pilot sequences to use have some notion of“orthogonality” in the frequency domain. In some embodiments,well-adapted Fourier-like sequences are used given by the row of thematrix F. For peer discovery in one exemplary peer to peer system:

${F = {{\sqrt{E_{s}}\begin{bmatrix}^{{j2\pi\Delta}\; f_{1}{T_{p} \cdot 0}} & ^{{j2\pi\Delta}\; f_{1}{T_{p} \cdot 1}} & \ldots & ^{{j2\pi\Delta}\; f_{1}{T_{p} \cdot 11}} \\^{{j2\pi\Delta}\; f_{2}{T_{p} \cdot 0}} & ^{{j2\pi\Delta}\; f_{2}{T_{p} \cdot 1}} & \ldots & ^{{j2\pi\Delta}\; f_{2}{T_{p} \cdot 11}} \\\vdots & \vdots & \ddots & \vdots \\^{{j2\pi\Delta}\; f_{8}{T_{p} \cdot 0}} & ^{{j2\pi\Delta}\; f_{8}{T_{p} \cdot 1}} & \ldots & ^{{j2\pi\Delta}\; f_{8}{T_{p} \cdot 11}}\end{bmatrix}} \in C^{8 \times 12}}},{{\Delta \; f_{k}} = \frac{{2k} - 1}{16T_{p}}}$

A suitable choice of 8 Fourier-like sequences and 12 pilot positionsfaciliatates the performance sequence detection and channel estimationof multi-interferers using Cadzow iterative denoising (CD) method andProny's method (or annihilating filter method, AF). This method, whichseeks to detect 2 spikes in the frequency domain, turns out to be veryefficient in our case. In various embodiments, we are looking at thefrequency domain for spikes. Alternatively to CD+AF, in someembodiments, more classical FFT-based decoding/estimation methods areused. Notice also that orthogonalization can be, and sometimes is,implemented by introducing artificial phase rotation to both datasymbols and pilot symbols, which is of practical interest in our case.

Various methods and apparatus related to joint iterative decoding withside codebook, e.g., interleaver information via, e.g., Pilot Code, willnow be described. In some peer to peer and wireless networks, a keyfeature is the ability of detecting and decoding several peersinterfering on a same physical resource. Various strategies can bedevised and used at a system level in order to efficiently use theavailable but limited air interface resource. For practicalimplementations of the physical layer, link level techniques aretraditionally based on successive interference cancelation. Today,modern coding theory provides a new framework for deriving efficientreceivers that are inherently iterative, hence low complexity, and stillquasi-optimal in the limit of large lengths. Various embodimentsimplement a method that takes advantage of probabilistic coding methodsby randomizing further the underlying graphical structure of the overallgraph code. This approach is well suited to implementations where jointiterative decoding of two or more interferers is considered. This codedesign approach is therefore particularly efficient in conjunction withhierarchical coding design used in some embodiments. In someembodiments, the graph code used by a particular peer as defined belongsto a very small subset of possible graphs; its index is potentiallyencoded by the non-coherent code. In some embodiments, peers usedifferent codes in order to improve the joint (coherent) iterativedecoding of the two (and, as a side effect, potentially, the codingitself). Various embodiments implement a practical code design for acoherent multi-user interference channel.

An example and application for one exemplary peer to peer communicationssystem will now be described. Consider the transmitter device (TX). TheTX chooses, e.g., at random or pseudo-randomly or following certainrules, a codebook in a list of possible codes. This can be, e.g., agiven sparse graph code or, in the particular case of peer discovery inone exemplary peer to peer communication system, this can be aninterleaver picked in a common set of possible interleavers. Then, theTX performs the following two tasks. The TX encodes the codebook indexusing a non-coherent code, which is further placed on a set of pilotpositions. This forms a “pilot” code aimed at being non-coherentlydecoded. The TX also encodes the information bits using its particularcodebook choice. For peer discovery in one exemplary peer to peersystem, each of the devices will share the same convolutional code. Eachdevice will then permute the encoded bits via its own interleaverchoice. From a pure coding viewpoint, different codebooks might bringbetter performance, especially if when short block lengths areconsidered, even in cases where it is not a priori required from aninformation theory perspective. Thus, in some embodiments differentcodebooks are used. Hence the described method can, and sometimes is,also be used with other decoders than joint iterative decoders.

Consider the receiver device (RX). First, the RX decodes thenon-coherent code in order to jointly decode the codebook index, e.g.,the interleaver index for peer discovery in the peer to peer system, andestimate the channel. Second, the RX builds the graphical structureassociated with coherent decoding of the two interferers in order toperform joint iterative decoding. Notice that this second decoding basedon a loopy factor graph is suboptimal in general. However, for thestrict viewpoint of probabilistic decoding, the irregularity andrandomness (introduced by the fact that, with a certain probability, thecodebooks of two interferers are different) will, in many cases, improvethe overall decoding performance. The RX, in some embodiments, possessesseveral receiving antennas to improve the decoding performance.

An exemplary application to wireless networks will now be described. Aparticularly good example is the peer discovery phase of one exemplarypeer to peer communications system. In one embodiment, peer discoveryuses small codewords, e.g., 60 complex symbols, obtained from aconvolutional encoder, in combination with 12 pilot symbols. Now,assume, e.g., that each TX picks uniformly at random one particularpilot codeword among 8 potential complex-valued codewords of length 12.Each of the 8 codewords encodes 3 bits that labels a particularinterleaver. Once a pilot codeword is chosen, the TX interleaves thecomplex outputs of the coherent (convolutional based) code accordingly.Various embodiments are well suited for use with convolutional codes anddifferent interleavers. In particular short convolutional codes workwell in this approach since the overall global code that they form whenassociated with interleaving is very strong. This is independent of thetype of decoding used to recover the information being communicated. Atthe RX, several, e.g., two, peers interfere on a particular peerdiscovery resource ID (PDRID) resource. In a first stage, in someembodiments, the RX will jointly estimate the channel and decode thenon-coherent pilot sequences. With probability 7/8, it will be able toseparate the two pilot sequences of largest strength and further assignto each of them a particular label. Hence it knows which particularinterleaver is associated with each of the two interfering peers. In asecond stage, the RX will perform joint iterative decoding of these two(or more) peers. The graphical model will be similar (slightly morecomplex) to the one of a turbo code (e.g., two BCJR decoders exchanginginformation that is permuted according to the decoded interleaverindices). If the two peers use a different interleaver (with probability7/8), then the associated joint factor graph has larger loops and,hence, is believed to be more efficient. The joint coding scheme itself(independently of the decoder) is more efficient in some practicalscenarios.

The techniques of various embodiments may be implemented using software,hardware and/or a combination of software and hardware. Variousembodiments are directed to apparatus, e.g., mobile nodes such as mobileterminals, base stations, communications system. Various embodiments arealso directed to methods, e.g., method of controlling and/or operatingmobile nodes, base stations and/or communications systems, e.g., hosts.Various embodiments are also directed to machine, e.g., computer,readable medium, e.g., ROM, RAM, CDs, hard discs, etc., which includemachine readable instructions for controlling a machine to implement oneor more steps of a method.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an example of exemplary approaches. Based upondesign preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged while remainingwithin the scope of the present disclosure. The accompanying methodclaims present elements of the various steps in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

In various embodiments nodes described herein are implemented using oneor more modules to perform the steps corresponding to one or moremethods, for example, signal processing, message generation and/ortransmission steps. Thus, in some embodiments various features areimplemented using modules. Such modules may be implemented usingsoftware, hardware or a combination of software and hardware. Many ofthe above described methods or method steps can be implemented usingmachine executable instructions, such as software, included in a machinereadable medium such as a memory device, e.g., RAM, floppy disk, etc. tocontrol a machine, e.g., general purpose computer with or withoutadditional hardware, to implement all or portions of the above describedmethods, e.g., in one or more nodes. Accordingly, among other things,various embodiments are directed to a machine-readable medium includingmachine executable instructions for causing a machine, e.g., processorand associated hardware, to perform one or more of the steps of theabove-described method(s). Some embodiments are directed to a device,e.g., communications node, including a processor configured to implementone, multiple or all of the steps of one or more methods of theinvention.

In some embodiments, the processor or processors, e.g., CPUs, of one ormore devices, e.g., communications nodes such as access nodes and/orwireless terminals, are configured to perform the steps of the methodsdescribed as being performed by the communications nodes. Theconfiguration of the processor may be achieved by using one or moremodules, e.g., software modules, to control processor configurationand/or by including hardware in the processor, e.g., hardware modules,to perform the recited steps and/or control processor configuration.Accordingly, some but not all embodiments are directed to a device,e.g., communications node, with a processor which includes a modulecorresponding to each of the steps of the various described methodsperformed by the device in which the processor is included. In some butnot all embodiments a device, e.g., communications node, includes amodule corresponding to each of the steps of the various describedmethods performed by the device in which the processor is included. Themodules may be implemented using software and/or hardware.

Some embodiments are directed to a computer program product comprising acomputer-readable medium comprising code for causing a computer, ormultiple computers, to implement various functions, steps, acts and/oroperations, e.g. one or more steps described above. Depending on theembodiment, the computer program product can, and sometimes does,include different code for each step to be performed. Thus, the computerprogram product may, and sometimes does, include code for eachindividual step of a method, e.g., a method of controlling acommunications device or node. The code may be in the form of machine,e.g., computer, executable instructions stored on a computer-readablemedium such as a RAM (Random Access Memory), ROM (Read Only Memory) orother type of storage device. In addition to being directed to acomputer program product, some embodiments are directed to a processorconfigured to implement one or more of the various functions, steps,acts and/or operations of one or more methods described above.Accordingly, some embodiments are directed to a processor, e.g., CPU,configured to implement some or all of the steps of the methodsdescribed herein. The processor may be for use in, e.g., acommunications device or other device described in the presentapplication.

While described in the context of an OFDM system, at least some of themethods and apparatus of various embodiments are applicable to a widerange of communications systems including many non-OFDM and/ornon-cellular systems.

Numerous additional variations on the methods and apparatus of thevarious embodiments described above will be apparent to those skilled inthe art in view of the above description. Such variations are to beconsidered within the scope. The methods and apparatus may be, and invarious embodiments are, used with CDMA, orthogonal frequency divisionmultiplexing (OFDM), and/or various other types of communicationstechniques which may be used to provide wireless communications linksbetween communications devices. In some embodiments one or morecommunications devices are implemented as access points which establishcommunications links with mobile nodes using OFDM and/or CDMA and/or mayprovide connectivity to the internet or another network via a wired orwireless communications link. In various embodiments the mobile nodesare implemented as notebook computers, personal data assistants (PDAs),or other portable devices including receiver/transmitter circuits andlogic and/or routines, for implementing the methods.

1. A method of operating a communications device to communicateinformation, the method comprising: monitoring a plurality of differentsets of communications resources; determining the amount of energyreceived on at least a first portion of said different sets ofcommunications resources; selecting a set of communications resourcesfrom said plurality of different sets of communications resources to usefor communication; selecting one of a plurality of different pilotsequences to use for said communication; and transmitting pilot signalsusing the selected one of the plurality of different pilot sequences andat least a second portion of the selected set of communicationsresources.
 2. The method of claim 1, wherein said selecting a set ofcommunications resources is based on the determined amount of energyreceived on said at least a first portion of said different sets ofcommunications resources.
 3. The method of claim 1, wherein saiddifferent pilot sequences in said plurality of different pilot sequencesare orthogonal.
 4. The method of claim 1, wherein transmitting pilotsignals includes introducing a first uniform phase rotation from onepilot signal to the next to produce a Fourier sequence, the methodfurther comprising: introducing a second uniform phase rotation which isa function of the first uniform phase rotation into data symbols to betransmitted using a third portion of the selected set of communicationsresources, said third portion not including said second portion.
 5. Themethod of claim 1, wherein said different pilot sequences in saidplurality of different pilot sequences include pilots which differ inphase but not amplitude.
 6. The method of claim 1, wherein selecting oneof a plurality of different pilot sequences includes making a pseudorandom selection of one of the plurality of different pilot sequences.7. The method of claim 6, wherein said selecting one of a plurality ofdifferent pilot sequences was for a first time period, the methodfurther comprising: changing to a different one of the plurality ofdifferent pilot sequences and using the different one of the pluralityof pilot sequences during a second time period which is subsequent tosaid first time period according to a predetermined function.
 8. Themethod of claim 1, further comprising: determining the amount of energyattributable to signals corresponding to different ones of saidplurality of different pilot sequences; and selecting one of theplurality of different pilot sequences based on the determined amount ofenergy attributable to the different individual ones of the plurality ofpilot sequences.
 9. The method of claim 8, wherein said selectingincludes selecting the pilot sequence which has the lowest amount ofenergy attributed to it.
 10. The method of claim 1, wherein saiddifferent sets of communications resources are sets of peer discoveryresources which recur in a predetermined timing structure used tocontrol timing in a communications network in which said wirelesscommunications device is located.
 11. The method of claim 1, whereineach set of communication resources is a set of contiguous OFDMtone-symbols corresponding to a single tone for a predetermined numberof symbol transmission time periods.
 12. A communications devicecomprising: means for monitoring a plurality of different sets ofcommunications resources; means for determining the amount of energyreceived on at least a first portion of said different sets ofcommunications resources; means for selecting a set of communicationsresources from said plurality of different sets of communicationsresources to use for communication; means for selecting one of aplurality of different pilot sequences to use for said communication;and means for transmitting pilot signals using the selected one of theplurality of different pilot sequences and at least a second portion ofthe selected set of communications resources.
 13. The communicationsdevice of claim 12, wherein said means for selecting a set ofcommunications resources selects based on the determined amount ofenergy received on said at least a first portion of said different setsof communications resources.
 14. The communications device of claim 12,wherein said different pilot sequences in said plurality of differentpilot sequences are orthogonal.
 15. The communications device of claim12, wherein said means for transmitting pilot signals includes means forintroducing a first uniform phase rotation from one pilot signal to thenext to produce a Fourier sequence, the communications device furthercomprising: means for introducing a second uniform phase rotation whichis a function of the first uniform phase rotation into data symbols tobe transmitted using a third portion of the selected set ofcommunications resources, said third portion not including said secondportion.
 16. The communications device of claim 12, wherein saiddifferent pilot sequences in said plurality of different pilot sequencesinclude pilots which differ in phase but not amplitude.
 17. A computerprogram product for use in a communications device, the computer programproduct comprising: a computer readable medium comprising: code forcausing at least one computer to monitor a plurality of different setsof communications resources; code for causing said at least one computerto determine the amount of energy received on at least a first portionof said different sets of communications resources; code for causingsaid at least one computer to select a set of communications resourcesfrom said plurality of different sets of communications resources to usefor communication; code for causing said at least one computer to selectone of a plurality of different pilot sequences to use for saidcommunication; and code for causing said at least one computer totransmit pilot signals using the selected one of the plurality ofdifferent pilot sequences and at least a second portion of the selectedset of communications resources.
 18. A communications device comprising:at least one processor configured to: monitor a plurality of differentsets of communications resources; determine the amount of energyreceived on at least a first portion of said different sets ofcommunications resources; select a set of communications resources fromsaid plurality of different sets of communications resources to use forcommunication; select one of a plurality of different pilot sequences touse for said communication; and transmit pilot signals using theselected one of the plurality of different pilot sequences and at leasta second portion of the selected set of communications resources; andmemory coupled to said at least one processor.
 19. The communicationsdevice of claim 18, wherein said at least one processor is configured tobase said selection of a set of communications resources on thedetermined amount of energy received on said at least a first portion ofsaid different sets of communications resources, as part of beingconfigure to selection a set of communications resources.
 20. Thecommunications device of claim 18, wherein said different pilotsequences in said plurality of different pilot sequences are orthogonal.